Objective:To explore the genotoxic potential and histopathological changes induced in liver,kidney,testis,brain and heart after using the antibiotic drug amoxicillin/clavulanic acid (4∶1).Methods:The study included chromosomal aberration analysis in bone-marrow and mouse spermatocytes,induction of sperm morphological abnormalities and histopathological changes in different body organs.The drug was administrated orally at a dose of 81 mg/kg body weight twice daily (Total =162 mg/kg/day) for various periods of time equivalent to 625 mg/men (twice daily).Results:The results revealed non-significant chromosomal aberrations induced after treatment with amoxicillin/clavulanic acid (AC) in both bone marrow and mouse spermatocytes after 7 and 10 days treatment.On the other hand,statistically significant percentages of sperm morphological abnormalities were recorded.Such percentage reached 8.10 ± 0.55,9.86 ± 0.63 and 12.12 ± 0.58 at the three time intervals tested (7,14and 35 days after the 1st treatment respectively) (treatment performed for 5 successive days) compared with 2.78 ± 0.48 for the control.The results also revealed histopathological changes in different body organs after AC treatment which increased with the prolongation of the period of therapy.Congestion of central vain,liver hemorrhage and hydropic changes in hepatocytes were noticed in the liver.Degenerative changes were found in kidney glomerulus and tubules while testis showed atrophy of seminiferous tubules,and reduction of spermatogenesis.AC also induced neurotoxicity and altered brain neurotransmitter levels.Hemorrhage in the myocardium,disruption of cardiac muscle fibers and pyknotic nuclei in cardiomyocytes were recorded as side effects of AC in heart tissue.Contusions:The results concluded that AC treatment induced sperm morphological abnormalities and histopathological changes in different body organs.Clinicians must be aware of such results while describing the drug.