Summary A prospective, dose-escalating, quasi-experimental clinical trial was conducted with a traditional healer using a decoction of Argemone mexicana for the treatment of malaria in Mali. The remedy was prescribed in three regimens: once daily for 3 days (Group A; n = 23); twice daily for 7 days (Group B; n = 40); and four times daily for the first 4 days followed by twice daily for 3 days (Group C; n = 17). Thus, 80 patients were included, of whom 80% were aged <5 years and 25% were aged <1 year. All presented to the traditional healer with symptoms of malaria and had a Plasmodium falciparum parasitaemia >2000/l but no signs of severe malaria. The proportions of adequate clinical response (ACR) at Day 14 were 35%, 73% and 65% in Groups A, B and C, respectively (P = 0.011). At Day 14, overall proportions of ACR were lower in children aged <1 year (45%) and higher in patients aged >5 years (81%) (P = 0.027). Very few patients had complete parasite clearance, but at Day 14, 67% of patients with ACR had a parasitaemia <2000/l. No patient needed referral for severe disease. Only minor side effects were observed. Further research should determine whether this local resource could represent a first-aid home treatment in remote areas.