ACTs reduce gametocyte carriage markedly, and therefore reduce transmission. This is very valuable in epidemic control. In the only randomized comparison reported, ACTs had a greater effect than primaquine on gametocyte carriage. In circumstances where an ACT is not used, a single oral dose of primaquine of 0.75 mg base/kg bw (45 mg base maximal for adults) combined with a fully effective blood schizonticide could be used to reduce transmission provided that it is possible to achieve high coverage (> 85%) of the population infected with malaria. This strategy has been widely used in South-East Asia and South America, although its impact has not been well documented. The single primaquine dose was well tolerated and prior testing for G6PD deficiency was not required. There is no experience with its use in Africa, where there is the highest prevalence of G6PD deficiency in the world. Primaquine should not be given in pregnancy. Whether there is any additional benefit in combining primaquine with an ACT is unknown. There is insufficient evidence to recommend this.