C5H7N3O
# C5H7N3O

$C_5H_7N_3O$ 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 (mecytosine)
