The effect of black seed oil ( Nigella sativa
oil) on parasitaemia, some serum and liver enzymes as well as some haematological parameters in Trypanosoma brucei
-infected rats was investigated. The results show there was low parasitaemia and extension of life span of rats from 12 days of the infected untreated (control) rats to 22 days for the infected black seed oil-treated rats. Results also show significant increases in activities of serum alkaline phosphatase as well as glutamate oxaloacetate and glutamate pyruvate transaminases with decreases in the liver enzyme activities. Protein concentrations show significant decreases in the serum and increases in the liver. There were also significant increases in the haemoglobin (Hb) concentration, packed cell volume (PCV), red blood cell (RBC), white blood cell (WBC) and platelet counts of infected oil-treated rats when compared with the infected untreated. We suggest that black seed oil has trypanocidal properties and probably stimulate the host immune system to control parasite proliferation thereby making it a possible agent for managing African sleeping sickness despite possible gradual damage to host organs as shown by increases in some serum enzymes.