Artemisinin-based combination therapy (ACT) is increasingly being adopted as the first-line treatment for malaria in sub-Saharan Africa. In September-November 2005, in New Halfa, eastern Sudan, the efficacy of artesunate-sulfadoxine-pyrimethamine (AS-SP) for the treatment of uncomplicated, Plasmodium falciparum was compared with that of artesunate-amodiaquine (AS-AQ). The artesunate was given at 4 mg/kg. day on days 0-2, with either a single dose of SP (25 mg sulfadoxine/kg) given on day 0, or AQ, at 10 mg/kg. day, given on days 0-2. Eighty-two of the patients treated (40 given AS-SP and 42 given AS-AQ) completed the 28 days of follow-up. On day 3 all the patients were afebrile and only one patient, in the AS-AQ group, was still parasitaemic. AS-SP appeared slightly more efficacious than AS-AQ but the differences were not statistically significant. Only one patient (2.5%) given AS-SP but four (9.5%) of those given AS-AQ were initially considered to be late treatment and parasitological failures, with all other patients showing an adequate treatment response. The PCR-corrected frequencies of cure were 97.5% for AS-SP and 95.2% for AS-AQ (P>0.05). No gametocytaemias were observed during the follow-up and, although mild adverse effects (nausea, vomiting, abdominal pain, dizziness and/or rash) were detected in 14 patients, they occurred at the same frequency in each treatment arm. It therefore appears that the AS-SP and AS-AQ combinations were both effective and safe for the treatment of uncomplicated, P. falciparum malaria in eastern Sudan.