C5H7N3O

C5H7N3O may refer to:


 * Methylcytosine
 * 5-Methylcytosine
 * 1-Methylcytosine, a nucleic acid in Hachimoji DNA
 * N(4)-Methylcytosine
 * 6-Methylcytosine
 * Methylisocytosine
 * 1-Methylisocytosine
 * 3-Methylisocytosine
 * 4-Methylisocytosine
 * 5-Methylisocytosine
 * 6-Methylisocytosine