5-carboxylcytosine (5-caC) was recently discovered as a DNA base formed as the final derivative of 5-methylcytosine via the oxidation of 5-hydroxymethylcytosine by TET hydroxylases. Our 5-carboxylcytosine ELISA Kit provides a simple, convenient microplate-based method to measure the amount of total 5-caC present in a variety of sample types. Detection is performed in a standard microplate reader.