Objectives: Muscarinic acetylcholine receptors play key roles in regulating many diverse physiological processes. Recent studies suggest that muscarinic receptors mediate some cellular events in hematopoietic cells. Muscarinic receptors are expressed in different human cells. cAMP an intracellular signaling molecule, is involved in a wide variety of physiological functions and stimulation of muscarinic receptors leads to the alteration of intracellular cAMP levels. The present study investigated muscarinic receptors mediated cAMP level in K562 chronic myelogenous leukemic cells.