Objective: investigation of the bio-effects of exposure to 2 gauss electromagnetic field (EMF) on blood elements, blood glucose, hepatocellular enzymes and bilirubin of mice and their possible modification by L-cysteine. Methods: the following groups were studied; (1) normal rats treated with saline; (2) normal rats treated with L-cysteine (18 mg/kg); (3) rats exposed to EMF for 21 days and treated with the vehicle (saline) during the exposure period; (4) rats exposed to EMF for 21 days and treated with L-cysteine (18 mg/kg orally, 3 times per week) during the exposure period; (5) rats exposed to EMF for 21 days and treated with the vehicle (saline) during the exposure period and for 45 days after exposure; (6) rats exposed to EMF for 21 days and treated with L-cysteine (18 mg/kg orally, 3 times per week) during the exposure period and for 45 days after exposure; Results: in rats exposed to low frequency EMF for 21 days (group2), marked increase in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in serum was observed. Plasma bilirubin level was raised. Meanwhile, significant decrease in plasma glucose levels occured after exposure to EMF. No significant changes were observed in haemoglobin level, red blood cells or total leucocytic count noted in rats exposed to EMF. The elevations in serum bilirubin, AST and ALT levels were reduced to near normal values in rats given L-cysteine druing the 21 days of exposure (group3). On the other hand, in rats examined 45 days after the end of the exposure period (group 3), no significant alterations were noted as regards bilirubin, AST, ALT and glucose levels in serum. Conclusions: these results suggest that (1) exposure to low frequency EMF of 50 Hz is associated with some degree of liver injury reflected in increased leakage of hepatoceular enzymes into plasma as well as an increase in serum bilirubin; (2) these alterations can be ameliorated by the administration of L-cysteine, as well as; (3) by limiting exposure to EMF.