Abstract: Medicinal plants have been widely used to enhance or regulate fertility in males. The purpose of our study is to evaluate the effects of methanol extract derived of celery (Apium graveolens L.) on the histological structure of some organs of the reproductive system in male experimental rats. This study was conducted on eighty experimental male rats (Sprague Dawely strain) weighing about 220 g each were used throughout the study and randomly assigned to four experimental groups of 20 rats each. Group I received normal saline (0.5 mL/kg) and serves as control. Group II is the vehicle groups. Group III and IV-gavaged daily for 30 days with 1 mL of the ethanol extract at doses of 213 mg/kg and 425 mg/kg body wt. After 30 days of treatments, under light ether anesthesia 24 h after the last treatment all rats were sacrificed and some organs as seminiferous tubules, tests, liver and kidney surgically removed weighed and a part of each was fixed in 10% formaldehyde for histological processes. The results of the effect of A. graveolens seeds ethanolic extract on diameter of seminiferous tubules showed that the treated groups showed a remarkable decrease in the diameter of seminiferous tubules in compression with control and vehicle groups. Light microscopic examination of hematoxylin and eosin stained sections of control and vehicle groups showed that the testicular tissues have many seminiferous tubules showing germinal epithelium with normal spermatogenesis process occur. The treated groups (213 mg/kg) showed complete loss of germinal cells in addition to reduction of the spermatogenesis process compared to the control group while at 425 mg/kg dose level sections showed complete loss of germinal cells and severely damage in the seminiferous tubules. However, results of the effect of A. graveolens seeds ethanolic extract on percentage of normal and abnormal seminiferous tubules are presented in a marked decrease in the percentage of normal seminiferous tubules appeared in both treated groups from 11 and 20% for 425 and 213 mg/kg, respectively, compared to the control group 57% and vehicle group 54%. Moreover, the abnormal tubules in both treated groups increased compared to the control and vehicle groups. Examination of histological sections through the liver of the control and vehicle groups showed normal hepatocytes that were arranged into hepatic plates; also both treated groups do not show any change. Histological examination of the cortex region of the kidney of the control and vehicle groups showed normal intact glomeruli and both proximal and distal tubules. Moreover, the treated groups at two dose level do not show any change. From the present study we conclude that the ethanolic extract of A. graveolens seed may act as antifertility agent. This is supported by the results that showed a decrease in the fertility parameters (sperm motility and sperm count), testosterone level, protein content of the testes, weight of the testes and seminal vesicle, diameter of seminiferous tubules and fertility rate. Histology of the testes of the treated groups showed a complete loss of the germ cells with arrest in the spermatogenesis process. Also, the 425 mg/kg treated group showed severe damage in the seminiferous tubules compared to the control and vehicle groups. On the other hand, histological examination of both liver and kidney of the treated groups does not show any signs of changes. These indicate that the ethanolic extract of A. graveolens seed may not have any signs of toxicity. Examination of histological sections through the liver of the control and vehicle groups showed normal hepatocytes that were arranged into hepatic plates; also both treated groups do not show any change. Histological examination of the cortex region of the kidney of the control and vehicle groups showed normal intact glomeruli and both proximal and distal tubules. Moreover, the treated groups at two dose level do not show any change. From the present study we conclude that the ethanolic extract of A. graveolens seed may act as antifertility agent. This is supported by the results that showed a decrease in the fertility parameters (sperm motility and sperm count), testosterone level, protein content of the testes, weight of the testes and seminal vesicle, diameter of seminiferous tubules and fertility rate. Histology of the testes of the treated groups showed a complete loss of the germ cells with arrest in the spermatogenesis process. Also, the 425 mg/kg treated group showed severe damage in the seminiferous tubules compared to the control and vehicle groups. On the other hand, histological examination of both liver and kidney of the treated groups does not show any signs of changes. Examination of histological sections through the liver of the control and vehicle groups showed normal hepatocytes that were arranged into hepatic plates; also both treated groups do not show any change. Histological examination of the cortex region of the kidney of the control and vehicle groups showed normal intact glomeruli and both proximal and distal tubules. Moreover, the treated groups at two dose level do not show any change. These indicate that the ethanol extract of A. graveolens seed may not have any signs of toxicity.