Human fascioliasis caused by Fasciola hepatica or Fasciola gigantica is an increasing global problem. The mainstay of current treatment is triclabendazole, but resistance in animals has been described, and it is not available in many countries. The antimalarial artesunate has an excellent safety profile, and there is increasing evidence of its efficacy against other parasites both in vitro and in vivo. We performed a study to investigate the usefulness of artesunate in symptomatic human fascioliasis; 100 patients were enrolled. Patients treated with artesunate were significantly more likely to be free of abdominal pain at hospital discharge (50/50 versus 44/50, P = 0.027, relative risk 1.14, 95% confidence interval 1.03-1.26), but the complete response rate at 3 months was lower than for patients treated with triclabendazole (38/50 versus 46/50, P = 0.05, RR 0.83, 95% CI 0.69-0.98, artesunate versus triclabendazole). There may be a role for artesunate in fascioliasis.