Background: The aim of the present study was to investigate the in vitro effects of mercury (Hg+2), lead (Pb+2), silver (Ag+2), tin (Sn+2), bismuth (Bi+3) and indium (In+3) ions on sperm creatine kinase. Methods: creatine kinase was isolated from human sperm homogenates after chromatography on a DEAE cellulose column. Results: At 60 µg ml-1 metal concentration, 70% of the creatine kinase activi...