Ligand binding for cholinergic muscarinic receptors with (3H) quinuclidinyl benzilate was performed on human detrusor smooth muscle from post surgical and postmortem sources. Following cystectomy, detrusor smooth muscle was serially sampled over an interval of 0 to 9 hours. (3H) quinuclidinyl benzilate binding on individual samples indicated that the total receptor density remained relatively unchanged. Postmortem specimens obtained from patients ranging in age from 1 day to 82 years were also assayed and the cholinergic receptor density was found to range between 18.4 to 82.1 fmoles/mg. of protein. All of the affinity constants from both sources were also in a relatively narrow range of 20.0 to 99.0 pmolar. The results of this study provide evidence for the usefulness of postmortem human tissue for evaluating cholinergic receptors in normal and dysfunctional bladder states.