A purine nucleoside hydrolase from Trypanosoma gambiense was purified 160-fold. Preferred substrates of the reaction were adenosine, inosine and guanosine with a maximum of activity at pH 5.4. Competitive inhibitors of the adenosine hydrolysis were dimethylallyl adenosine, 6-methylmercaptopurine riboside, tubercidin, formycin B, 6-mercaptopurine riboside and deoxyadenosine. A metabolic scheme of adenosine nomophosphate salvage synthesis is discussed.