The purpose of this study was to investigate the effects of Endosulfan [6,7,8,9, 10, 10-hexachloro- 1,5. 5a. 6, 9, 9 a hexahydro- 6, 5, methano - 2, 4, 3-benzo (e) dioxathpiepin 3- oxide], Mavrik [alpha-cyano -3-phenoxybenzyl M -(2 chloro-alpha-alpha-alpha-triflouro-p-tolyl)- D - valinate], 2,4-D (2,4-Dichlorophenoxyacetic acid) and Neoran (isopropyl -4,4-dibromobenzilate) on serum amylase (EC 188.8.131.52), creatine kinase (CK; EC 184.108.40.206) aspartate amino transferase (AST; EC 220.127.116.11), alanine aminotransferase (ALT; EC 2..6.1.2), alkaline phosfatase (ALP; EC 18.104.22.168), gamma glutamyl transferase (GGT; EC 22.214.171.124) and lactate dehydrogenase (LDH; EC 126.96.36.199). I-50 values of chemicals caused inhibition were determined by means of activity percentage -[I] diagrams. Endosulfan had effect of inhibition only on AST. The I-50 value of chemical was determined as 3.13x10(-4) M. Mavrik had effects of inhibition on AST, ALT, ALP and LDH. The values of I-50 were 7.83x10(-4) M, 1.17x10(-4), 1.23x10(-3) M and 2.23x10(-3) M, respectively. 2,4-D had effects of inhibition on ALT, ALP, GGT and LDH. The I-50 values of chemical were 6.97x10(-2) M, 5.05x10(-2) M, 2.35x10(-2) M, 1.07x10(-2) M, respectively. On the other hand, Neoran had effects of inhibition of all enzymes except amylase. I-50 values of this compound on other enzymes (CK, AST, ALT, ALP, GGT and LDH) were 4.41x10(-4) M, 5.06x10(-3) M, 2.40x10(-3) M, 5.23x10(-3) FA,4.4x10(-3) M, 5.97x10(-3) M, respectively.