Perfluoro-n-decanoic acid (PFDA) is a member of a family of surfactants with numerous industrial applications. The acute toxicity of PFDA is characterized by body wasting and delayed lethality. Recent reports have indicated that the effects of PFDA may involve an action on the structure of biological membranes which results in an alteration of function. In the present study we extend our work on the membrane actions of PFDA by examining its effects on myocardial beta-adrenoceptor binding characteristics and adenylate cyclase. Following a single injection of PFDA the apparent number of beta-receptor binding sites was reduced compared to pair-fed controls. This change in beta-receptor binding capacity was reflected in a reduced ability of norepinephrine to activate adenylate cyclase. No alterations were observed in basal adenylate cyclase activity or in the ability of NaF or guanylyl imidodiphosphate to stimulate the enzyme. The fatty acid composition of the heart was changed by PFDA treatment. Our results suggest that the toxic effects of PFDA may be due to an alteration of the membrane lipid bilayer leading to changes in the functional activity of myocardial membranes.