The primary goal of this study is to quantify the benefit of adding artesunate to amodiaquine in treating patients with uncomplicated P. falciparum malaria, in a low transmission area in Colombia. The benefit will be assessed in terms of:

• Efficacy
• Tolerability
• Time of fever clearance
• Time of parasite clearance
• Proportion of gametocyte carriers

Inclusion Criteria:

1. pure P. falciparum infection
2. parasitaemia >500 and <50,000 asexual parasites/μL (subsequently the lower limit was modified to >250 asexual parasites/μL)
3. age between 1 and 65 years old
4. availability to return for follow-up

Exclusion Criteria:

1. Pregnancy
2. history of allergy to the study drugs
3. history of taken complete treatment with an antimalarial drug in the previous 72 hours or sulphas, clindamycin or tetracycline in the previous week
4. have a medical history of untreated hypertension or chronic heart, kidney or liver disease
5. present any danger signs of severe malaria.