The present study aimed to evaluate the acute (14 days) and sub-acute (28 days) oral toxicity of ethanolic extract of Leucas aspera (EELA) on albino mice and adult Wistar rats. Acute dosage was 2000mg/kg body weight while sub-acute dosage was 100, 200 and 400 mg/kg b.w. per day of the extract. All morphological, biochemical, hematological changes, in addition to mortality and body weight changes were recorded. Histopathological study was done on vital organs. EELA did not show mortality up to 2g/kg b.w. in the acute toxicity studies. The sub-acute toxicity study demonstrated no significant changes in body weight, food, and water intake. Hematological parameters and biochemical analytes inclusive of glucose, urea, creatinine, total cholesterol, total protein and total bilirubin did not show statistically significant differences between the control and treated groups while the activities of aminotransferases was slightly increased in group IV (P < 0.001) animals. No morphological changes were observed in the histopathological analysis of the major vital organs (liver, kidney, heart, spleen, lungs and brain) tested. In conclusion, the results of this study suggest the non-toxic nature of the ethanolic extract of Leucas aspera at normal therapeutic doses.