Occupational exposure to petroleum has been reported to have toxic effects on various organs and systems. The purpose of this research is to investigate the potential risk associated with exposure of non-pregnant women of child bearing age selling PMS (WSP) in Okada-Ore Road, Edo State, Nigeria using batteries of haematological parameters and level of MetHb as an indirect blood biomarker of exposure to benzene in PMS. 100 women each for both test and control population within the age 18-34 years were recruited into the study.We observed that women exposed to petroleum had a significant higher Met Hb than control group. The red cell indices decreased with increase in years of exposure. Red blood picture of subject within 1-3 years of exposure shows that of dimorphic blood picture with microcytic normocytic hypochromic cells as predominant features.Platelet count decreased with level of Subjects above 5 years of exposure resulting in mild thrombocytopenia with few blasts. The route of exposure to PMS is by mouth suction due to conservation of time for maximum profit making and skin contamination.