The study was carried out to assess the efficacy of melarsomine dihydrochloride (Cymelarsan®) against experimental Trypanosoma evansi infection (surra) in pigs. Specifically, the study aimed to: (a) determine the time of disappearance of T. evansi from the blood of pigs after treatment with two different doses of melarsomine dihydrochloride; (b) compare the bodyweight and rectal temperature of control pigs and those infected and treated with melarsomine dihydrochloride; (c) observe any apparent side effects of melarsomine dihydrochloride among treated pigs; and, (d) compare the efficacy of two different doses of melarsomine dihydrochloride. Sixteen, apparently healthy, 40-50 days old pigs (piglets) were used in the study. The piglets were randomly allocated into four treatments with 4 animals each group: T0= uninfected-untreated; T1=infected-untreated; T2= infected, treated with melarsomine dihydrochloride at 0.25 mg kg-1 bodyweight (BW); and, T3= infected, treated with melarsomine dihydrochloride at 0.5 mg kg-1 BW. Each animal in Treatments 1-3 was inoculated with approximately 100,000 T. evansi (Mindanao isolate). Single intramuscular treatment with the drug was done two weeks after infection. Parasitemia was monitored daily after inoculation and at 1, 3 and 24 hours, and every 3-4 days for 90 days post treatment (pt) using microhematocrit centrifugation technique (MHCT) and/or mouse inoculation test (MIT). Rectal temperatures were monitored daily for 3 days prior to inoculation and every 3-4 days after inoculation, and weekly, pt, for 4 weeks. Bodyweights were taken prior to inoculation and treatment, and weekly, pt, for 4 weeks. Trypanosomes were not detected in the blood of pigs an hour, pt. There were no significant differences on the bodyweights among pigs and rectal temperatures of T. evansi-infected pigs returned to normal after melarsomine treatment. Side effects were not observed among melarsomine-treated pigs. Pigs treated with 0.5 mg kg-1 BW dose were f