In Southeast Asia Trypanosoma evansi infection is a disease of economic importance since it affects the health of buffalo, cattle and swine. The acute stage symptoms include abortion, central nervous system disorder and even death, and in the chronic condition working capacity and productivity of the animals are affected. A polymerase chain reaction (PCR)-based detection technique has been developed with a sensitivity of 0.5 pg of parasite DNA or one single parasite in 10 microliters of blood samples which were allowed to clot and then boiled before DNA amplification. This permitted storage of blood collection at ambient temperature for at least one month. Phosphate-saline-glucose solution, normally used as trypanosome maintenance buffer, inhibited PCR. Although DNA primers used were derived from T. evansi specific sequence, amplification of the genome of T. brucei and T. equiperdum generated the same 227 bp fragment. This method should now make it possible to detect infections in livestock in the very early stages where microscope examination is equivocal and to monitor groups of animals after trypanocidal treatment.