There are some 140 different genotypes of G6PD deficiency with corresponding enzyme activity phenotypes that vary from mild to severe. Primaquine sensitivity phenotypes are known only in 3 variants; African A-, Mahidol, and Mediterranean B-, representing mild, moderate and severe sensitivity, respectively. Correlation between severity of enzyme activity loss and sensitivity to primaquine is believed to exist but has not been confirmed with clinical observations. In Cambodia, G6PD deficiency is common, with a prevalence ranging from 13.4% to 26.1% in males and 3.1% to 4.3% in females, depending on the sampled population. G6PDViangchan is the most frequent variant. G6PD deficiency may be diagnosed by a variety of spectrophotometric enzyme activity assays or DNA-based detection of specific mutations. These tests, however, require relatively sophisticated laboratory capacities. Qualitative tests for this disorder based upon reduction of NADP+ by G6PD have been used for screening patients in the absence of laboratory facilities prior to administration of primaquine therapy. Since 1979, the fluorescent spot test is recommended as the most suitable method for screening in the field, despite the need for an UV lamp, water bath incubator, and micropipettor. Such equipment and the skills to use them are rarely available in malaria endemics areas. Consequently, providers in such settings invite substantial risk of harm by prescribing primaquine therapy and the drug is thus rarely used. Rapid diagnostic tests are an alternative and attractive option because they are generally easy to use and could be used alongside malaria RDTs. However, the only available test named BinaxNOW G6PD testTM which has been recently evaluated, presents a major drawback with the need to perform the test within a temperature ranging from 18 to 25uC, imposing limited usefulness in tropical malaria-endemic countries. AccessBio has developed a new experimental RDT called CareStartTM G6PD deficiency screening test and its first assessment outside of their laboratories is reported here, by comparing its performance to the gold standard, quantitative spectrophotometric estimation of G6PD enzyme activity. In many malaria endemic countries like Cambodia that are engaging in malaria elimination, the BAY 73-4506 introduction of primaquine, for transmission blocking or radical cure, in national malaria management guidelines remains a major safety challenge for policy makers. The availability of an accurate, user-friendly, fieldadapted RDT for G6PD deficiency would be a major step forward. The main advantages for using this drug are both the prevention of P. falciparum transmission from malaria infected patients by killing mature gametocytes and the radical cure P. vivax infections by preventing relapses of the persistent liver parasites. However, it is well-known since 1956, the use of primaquine is not safe in people with erythrocyte glucose-6-phosphate dehydrogenase deficiency. The most common clinical manifestation is an acute hemolytic anaemia.