Abstract The binding of adenosine 3′,5′-monophosphate (cAMP) to its specific protein kinase in the presence of hydroxyapatite, collagen and chondroitin sulfate was studied. Only hydroxyapatite inhibited cAMP binding to the protein kinase. To overcome this inhibition, a new and simple technique for the extraction of cAMP from chick and cat bone was developed in which cation interference was minimized. The new methodology consisted of first cleansing fresh bone of marrow and mechanically pulverizing it. the bone fragments are then mixed with water, boiled and homogenized. The homogenate is centrifuged and aliquots of the supernatant fraction assayed for cAMP. The cAMP concentrations of cat and chick bone were found to be between 0.21 and 0.40 pmoles/mg of bone. Furthermore, in response to parathyroid hormone, elevated cAMP levels were detected. The precision, reproducibility and sensitivity of the technique is high. Additional studies with phosphodiesterase confirmed that the method is specific for the cyclic nucleotide.