In the present study we report data obtained from the evaluation of subjects occupationally exposed to pesticide mixtures from Santa Fe province, Argentina, using biomarkers for butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) activities, catalase (CAT), lipid peroxidation (by TBARS assay) and the Damage Index Comet Assay (DICA). Our results showed an AChE inhibition (25% and 15% in directly and indirectly groups, respectively) in relation to controls with no significant modifications in BChE. TBARS levels were higher (51%) in pesticide sprayers while CAT activity was reduced in both, applicators (61%) and non-applicators (43%). DICA was significantly increased in direct (83%) and indirect (98%) exposed groups, compared with controls. These results showed modifications in lipid peroxidation, antioxidant defence system, and DNA damage in lymphocytes of exposed workers. Further investigations are suggested in order to link our findings with adverse health effects observed in chronic pesticide toxicity, where oxidative damage plays a pathophysiological role.