Abstract: To assess the adverse health effects of pesticides on occupationally exposed workers, a cohort of pesticide sprayers, employed in Riyadh municipality, were interviewed and examined for changes in hematological profile, blood AChE activity, serum enzymes reflecting hepatotoxicity (AST, ALT and ALP) and markers of nephrotoxicity (urea and creatinine). There was a significant decrease in AChE activity (p<0.001) in pesticide workers (n = 43) relative to the control group (n = 10). No significant differences were detected in hematological parameters, except for WBC count which was significantly higher (p<0.01) in pesticides workers compared to the control group. Slight increases were observed in liver and kidney functions in the exposed group. The results indicated the need for official regulations and interventions enforced to reduce workers overexposure to pesticides throughout the Kingdom of Saudi Arabia.