This high throughput, colorimetric, competitive immunoassay, for the quantitative determination of cyclic AMP in tissue samples, uses a cAMP polyclonal antibody to bind, in a competitive manner, the cAMP in the standards or sample. Cyclic AMP is one of the most important secondary messengers involved as a modulator of physiological processes. It is also involved in regulating neuronal, glandular, cardiovascular, immune and other functions and actions.