Introduction: Formaldehyde (FA) is a chemical, traditionally used in pathology and anatomy laboratories as a tissue preservative. Many studies clearly indicated that FA can induce genotoxic effects in peripheral blood lymphocytes. Aim of work: to evaluate the genotoxic effects of formaldehyde among medical and paramedical personnel in The Histopathology Laboratory. Materials and Methods: The study was conducted in histopathology laboratory including 30 workers occupationally exposed to formaldehyde and 29 persons from other lab in kasr Al Aini hospital matching the exposed group for age, sex and socioeconomic status with no history of occupational exposure to formaldehyde. A questionnaire was done including inquiries about age, sex, occupational history and special habits. All participants were subjected to the following laboratory investigations: measuring DNA protein crosslink (DPC), sister chromatid exchange (SCE) and micronucleus (Mn) frequency in peripheral blood lymphocytes. Environmental monitoring of the work place was done to measure the level of FA at different place in the pathology lab. Results: This study showed statistically significant increase of DPC with significant increase in sister chromatid exchange (SCE) and micronucleus MN in peripheral blood lymphocytes. Conclusion: The studied group was exposed to formaldehyde level above the exposure limits recommended by NIOSH, ACGIH and OSHA with adverse health effects in the form of increase in DPC, SCE and Mn as genotoxicity biomarkers. These genotoxicity biomarkers are considered to play an important role in the carcinogenesis of FA.