| month | day | visitor | score | home | score | 
|---|
| November | 3,  2003 | Celtics | 102 | Grizzlies | 85 | 
| November | 5,  2003 | Celtics | 110 | 76ers | 119 | 
| November | 6,  2003 | Celtics | 93 | Pacers | 95 | 
| November | 8,  2003 | Pistons | 91 | Celtics | 117 | 
| November | 15,  2003 | 76ers | 113 | Celtics | 110 | 
| November | 16,  2003 | Celtics | 97 | Spurs | 81 | 
| November | 20,  2003 | Pistons | 91 | Celtics | 110 | 
| November | 21,  2003 | Rockets | 96 | Celtics | 104 | 
| November | 22,  2003 | Cavaliers | 115 | Celtics | 117 | 
| November | 28,  2003 | Raptors | 114 | Celtics | 112 | 
| November | 29,  2003 | Celtics | 108 | Nuggets | 102 | 
| December | 4,  2003 | Celtics | 134 | Knicks | 120 | 
| December | 5,  2003 | Celtics | 111 | Lakers | 105 | 
| December | 7,  2003 | Blazers | 109 | Celtics | 119 | 
| December | 8,  2003 | Heat | 98 | Celtics | 83 | 
| December | 9,  2003 | Celtics | 102 | Mavericks | 97 | 
| December | 10,  2003 | Celtics | 95 | Bucks | 90 | 
| December | 16,  2003 | Hornets | 103 | Celtics | 119 | 
| December | 19,  2003 | Celtics | 134 | Magic | 108 | 
| December | 21,  2003 | Celtics | 89 | Hornets | 112 | 
| December | 24,  2003 | Celtics | 102 | Clippers | 110 | 
| January | 2,  2004 | Clippers | 110 | Celtics | 112 | 
| January | 3,  2004 | Raptors | 112 | Celtics | 121 | 
| January | 4,  2004 | 76ers | 111 | Celtics | 86 | 
| January | 7,  2004 | Celtics | 113 | Knicks | 122 | 
| January | 9,  2004 | Heat | 102 | Celtics | 71 | 
| January | 10,  2004 | Hawks | 107 | Celtics | 89 | 
| January | 11,  2004 | Celtics | 107 | Nets | 102 | 
| January | 15,  2004 | Jazz | 104 | Celtics | 119 | 
| January | 17,  2004 | Bullets | 109 | Celtics | 86 | 
| January | 18,  2004 | Celtics | 115 | 76ers | 92 | 
| January | 20,  2004 | Celtics | 118 | Sonics | 99 | 
| January | 21,  2004 | Celtics | 92 | Heat | 97 | 
| January | 23,  2004 | Celtics | 118 | Warriors | 108 | 
| January | 25,  2004 | Celtics | 89 | Suns | 109 | 
| January | 30,  2004 | Celtics | 111 | Magic | 124 | 
| January | 31,  2004 | Pacers | 92 | Celtics | 115 | 
| February | 1,  2004 | Celtics | 124 | Knicks | 125 | 
| February | 4,  2004 | Celtics | 125 | Bullets | 94 | 
| February | 8,  2004 | Bulls | 91 | Celtics | 114 | 
| February | 9,  2004 | Celtics | 98 | Pistons | 95 | 
| February | 10,  2004 | Knicks | 114 | Celtics | 118 | 
| February | 11,  2004 | Nets | 105 | Celtics | 106 | 
| February | 13,  2004 | Kings | 104 | Celtics | 122 | 
| February | 17,  2004 | Magic | 94 | Celtics | 124 | 
| February | 18,  2004 | Spurs | 81 | Celtics | 85 | 
| February | 23,  2004 | Celtics | 99 | Bullets | 108 | 
| February | 24,  2004 | Celtics | 96 | Bullets | 93 | 
| February | 26,  2004 | Celtics | 86 | Bucks | 98 | 
| February | 27,  2004 | Nuggets | 98 | Celtics | 135 | 
| March | 1,  2004 | Celtics | 99 | Heat | 102 | 
| March | 2,  2004 | 76ers | 89 | Celtics | 112 | 
| March | 5,  2004 | Bullets | 105 | Celtics | 100 | 
| March | 6,  2004 | Celtics | 92 | Nets | 83 | 
| March | 8,  2004 | Celtics | 91 | Nets | 74 | 
| March | 9,  2004 | Knicks | 103 | Celtics | 129 | 
| March | 11,  2004 | Wolves | 108 | Celtics | 93 | 
| March | 12,  2004 | Celtics | 87 | Bulls | 120 | 
| March | 13,  2004 | Lakers | 105 | Celtics | 117 | 
| March | 14,  2004 | Celtics | 110 | Blazers | 98 | 
| March | 15,  2004 | Magic | 111 | Celtics | 113 | 
| March | 18,  2004 | Celtics | 123 | Magic | 91 | 
| March | 19,  2004 | Celtics | 116 | Bulls | 106 | 
| March | 20,  2004 | Celtics | 64 | Heat | 91 | 
| March | 22,  2004 | Celtics | 98 | Cavaliers | 85 | 
| March | 24,  2004 | Celtics | 108 | Jazz | 104 | 
| March | 26,  2004 | Warriors | 88 | Celtics | 121 | 
| March | 27,  2004 | Pacers | 84 | Celtics | 120 | 
| March | 29,  2004 | Celtics | 105 | Rockets | 113 | 
| March | 30,  2004 | Celtics | 109 | Raptors | 112 | 
| April | 1,  2004 | Celtics | 94 | Wolves | 106 | 
| April | 3,  2004 | Celtics | 96 | Hawks | 116 | 
| April | 8,  2004 | Sonics | 57 | Celtics | 78 | 
| April | 9,  2004 | Hornets | 107 | Celtics | 103 | 
| April | 10,  2004 | Cavaliers | 101 | Celtics | 109 | 
| April | 13,  2004 | Grizzlies | 110 | Celtics | 96 | 
| April | 16,  2004 | Hawks | 104 | Celtics | 99 | 
| April | 17,  2004 | Mavericks | 98 | Celtics | 109 | 
| April | 20,  2004 | Bucks | 83 | Celtics | 81 | 
| April | 21,  2004 | Celtics | 80 | Kings | 125 | 
| April | 22,  2004 | Nets | 98 | Celtics | 79 | 
| April | 25,  2004 | Suns | 82 | Celtics | 96 | 
| Post | 1,  2004 | Celtics | 77 | Heat | 96 | 
| Post | 2,  2004 | Celtics | 80 | Heat | 72 | 
| Post | 3,  2004 | Heat | 76 | Celtics | 80 | 
| Post | 4,  2004 | Heat | 73 | Celtics | 88 | 
| Post | 5,  2004 | Celtics |  | Heat |  | 
| Post | 8,  2004 | Celtics | 104 | Knicks | 113 | 
| Post | 9,  2004 | Celtics | 93 | Knicks | 106 | 
| Post | 10,  2004 | Knicks | 108 | Celtics | 112 | 
| Post | 11,  2004 | Knicks | 104 | Celtics | 111 | 
| Post | 12,  2004 | Celtics | 102 | Knicks | 106 | 
| Post | 13,  2004 | Knicks | 105 | Celtics | 111 | 
| Post | 14,  2004 | Celtics | 104 | Knicks | 95 | 
| Post | 15,  2004 | Celtics | 93 | Bulls | 119 | 
| Post | 16,  2004 | Celtics | 99 | Bulls | 117 | 
| Post | 17,  2004 | Bulls | 108 | Celtics | 97 | 
| Post | 18,  2004 | Bulls | 118 | Celtics | 110 | 
| Post | 19,  2004 | Celtics |  | Bulls |  | 
| Post | 20,  2004 | Bulls |  | Celtics |  | 
| Post | 21,  2004 | Celtics |  | Bulls |  |