| CYP1 | Drug and steroid (especially estrogen) metabolism | 3 subfamilies, 3 genes, 1 pseudogene | CYP1A1, CYP1A2, CYP1B1 |
| CYP2 | Drug and steroid metabolism | 13 subfamilies, 16 genes, 16 pseudogene | CYP2A6, CYP2A7, CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP2F1, CYP2J2, CYP2R1, CYP2S1, CYP2U1, CYP2W1 |
| CYP3 | Drug and steroid (including testosterone) metabolism | 1 subfamily, 4 genes, 2 pseudogenes | CYP3A4, CYP3A5, CYP3A7, CYP3A43 |
| CYP4 | Arachidonic acid or fatty acid metabolism | 6 subfamilies, 12 genes, 10 pseudogenes | CYP4A11, CYP4A22, CYP4B1, CYP4F2, CYP4F3, CYP4F8, CYP4F11, CYP4F12, CYP4F22, CYP4V2, CYP4X1, CYP4Z1 |
| CYP5 | Thromboxane A2 synthase | 1 subfamily, 1 gene | CYP5A1 |
| CYP7 | Bile acid biosynthesis 7-alpha hydroxylase of steroid nucleus | 2 subfamilies, 2 genes | CYP7A1, CYP7B1 |
| CYP8 | Varied | 2 subfamilies, 2 genes | CYP8A1 (prostacyclin synthase), CYP8B1 (bile acid biosynthesis) |
| CYP11 | Steroid biosynthesis | 2 subfamilies, 3 genes | CYP11A1, CYP11B1, CYP11B2 |
| CYP17 | Steroid biosynthesis, 17-alpha hydroxylase | 1 subfamily, 1 gene | CYP17A1 |
| CYP19 | Steroid biosynthesis: aromatase synthesizes estrogen | 1 subfamily, 1 gene | CYP19A1 |
| CYP20 | Unknown function | 1 subfamily, 1 gene | CYP20A1 |
| CYP21 | Steroid biosynthesis | 2 subfamilies, 1 gene, 1 pseudogene | CYP21A2 |
| CYP24 | Vitamin D degradation | 1 subfamily, 1 gene | CYP24A1 |
| CYP26 | Retinoic acid hydroxylase | 3 subfamilies, 3 genes | CYP26A1, CYP26B1, CYP26C1 |
| CYP27 | Varied | 3 subfamilies, 3 genes | CYP27A1 (bile acid biosynthesis), CYP27B1 (vitamin D3 1-alpha hydroxylase, activates vitamin D3), CYP27C1 (unknown function) |
| CYP39 | 7-alpha hydroxylation of 24-hydroxycholesterol | 1 subfamily, 1 gene | CYP39A1 |
| CYP46 | Cholesterol 24-hydroxylase | 1 subfamily, 1 gene | CYP46A1 |
| CYP46 | Cholesterol biosynthesis | 1 subfamily, 1 gene, 3 pseudogenes | CYP51A1 (lanosterol 14-alpha demethylase) |
