The ethanolic leaf extract of Hyptis suaveolens was evaluated for antimalarial activity against Plasmodium berghei in infected mice. In the 4 day suppressive test, 60 male and female albino mice (weight: 18-23 g) were infected and treatment began immediately (Day 0), while administration started 72 hours post infection in the curative test. For each test, mice were divided into 5 groups of 12 animals; each group was administered one of the following: 10 mg/kg, 25 mg/kg and 50 mg/kg of the crude extract, 5 mg/kg of chloroquine phosphate or 0.2 ml normal saline for four consecutive days. Thin blood smears were prepared and examined microscopically under x 100 objective on day 4 to day 7 and the percentage parasitaemia were recorded. On day 7 the red blood cells (RBC), white blood cells (WBC), haemoglobin (Hb) and packed cell volume (PCV) were evaluated. The extract demonstrated dose-dependent inhibition effect on the parasites with 42.76% and 18.03% at 50 mg/kg, 33.69% and 10.22% at 25 mg/kg for suppressive and curative tests respectively, while at 10 mg/kg, 22.39% and 6.06% suppression were recorded in the suppressive and curative tests respectively. The RBC, HB and PCV values decreased while there was an increase in WBC compared with that of the control.