Stimulatory effects of saturated fatty acids consisting of 4 (butyrate), 8 (octanoate), 12 (laurate) and 16 (palmitate) carbon atoms, as well as acetylcholine on pancreatic amylase release were assessed in tissue segments isolated from sheep, rats, hamsters, field voles and mice. The amount of amylase release induced by the fatty acids (1 mumol.l-1 to 10 mml.l-1) and by acetylcholine (10 nmol.l-1 to 100 mumol.l-1) increased in a concentration-dependent manner, and the maximum response in response to the fatty acids was obtained at the maximal dose used. The maximum increase in amylase release in response to butyrate or octanoate was highly and significantly (r = 0.974, P < 0.001) dependent on the log value of the mean body mass in the following order: sheep > rats > hamsters > field voles > mice. On the other hand, the response to laurate and palmitate was variable among animal species. Addition of atropine (1.4 mumol.l-1) to the medium did not reduce the responses to octanoate stimulation, but significantly reduced acetylcholine-induced responses, implying that the effects of the fatty acids were not mediated through activation of muscarinic acetylcholine receptors. Reduction of calcium ion concentration in the medium significantly inhibited the responses induced by the fatty acids and acetylcholine, suggesting that amylase release depends on extracellular calcium ions.