The effects of ethanol, monofluoro- and trifluoroethanol on the hydrolysis of ATP and coupled Ca2+ translocation by sarcoplasmic reticulum Ca(2+)-ATPase (EC 3.6.1.38) were measured. All three alcohols had parallel effects on the enzyme activities at concentrations up to 200 mM, suggesting a similar mechanism of action. 19F nuclear magnetic resonance spectroscopy was used to investigate their site of action in the purified enzyme.