<p class="ql-align-justify"><em style="color: black;">The toxicological effects of ethanolic extract of Parquetina nigrescens leaves (EEPNL) on letrozole-induced polycystic ovarian syndrome (PCOS) in Wistar rats were evaluated. Twenty female Wistar rats (170.81 ± 5.25g) were randomly assigned into 5 groups (A - E) of four animals each. Animals in group A received 1 ml of distilled water and group B-E received 1mg/kg body weight of letrozole daily basis for a period of 21 days orally. The letrozole-treated groups, B-E, were then administered 1 ml of distilled water, co-administration of 7.14mg/kg of metformin and 2mg/kg clomiphene citrate (reference drug), 50 mg/kg b.wt of EEPNL and 100 mg/kg b.wt of EEPNL respectively for a period of 14 days. The animals were sacrificed 24 hours after the last treatment dose and the blood obtained via jugular puncturing was used in determining some toxicological indices such as liver function indices (albumin, bilirubin, globulin and total protein), kidney function indices (Urea, uric acid and creatinine), and enzyme assay (Alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase). The result revealed mild alterations in the parameters under studied in this work and this suggests that the ethanolic leaf extract of Parquetina nigrescens at doses investigated may be safe when used in the treatment of PCOS.</em></p><p><br></p>