BACKGROUND:Cyclophosphamide (CPA) is an anti- cancer drug, used in chemotherapy. This isa toxic drug whichtargets the cancer cellsand also the normal cells of the body. The original compound is inactive in vitro and exercises its biologic action through metabolites, chiefly phosphoramidemustard. The objective is to study the harmful effects of this drug on liver and kidney tissues.METHODS: To study the effect of cyclophosphamide on histology of liver and kidney, 40 adult male mice were taken and divided into twogroups: control and test. Those in the test group were injected with the drug at dosesof 100, 200, 250 mg/kg body weight. They were then sacrificed on day 7, 28 and 42. The liver and kidney tissue was processed, sectioned and stained with Haematoxylin and Eosin. RESULTS:Pathological changes were seen in the tissue within 7days in high doses and after 28 days in low doses.  As the dosage and the days administered increased, the changes were prominently seenand widespread. Pathology ranging from mild infiltration to necrosis and finally cytolysis wereseenin liver and kidney tissue. CONCLUSION: Our study has demonstrated the effect of a progressiveincrease in dosage of cyclophosphamide in albino mice, and pathological alterations were observed in histology of liver and kidney by sequentially increasing both the dosage and duration of treatment.  Subsequently,regular monitoring of liver and kidney function tests in patients undergoing chemotherapeutic regimen with administration of ahepato and nephroprotectiveagent becomes vital.KEYWORDS:cyclophosphamide, histopathology, hepatotoxicity, nephrotoxicity, chemotherapy