The study was designed to evaluate the current efficacy of this combination therapy against P. vivax, given the possibility of misuse or inadequate adherence to the regimen due to its lengthy treatment duration, in one of a vivax-endemic area in southwest Ethiopia. A 42-day in vivo drug efficacy study was carried out as an open, two arm clinical trial involving 192 patients with uncomplicated P. vivax mono infection. Participants were allocated into two groups: supervised (n = 96) and unsupervised (n = 96). Both groups received CQ, 25 mg/kg over 3 days) and PQ, 0.25 mg/kg/day for 14 days). In the supervised group, treatment was administered under direct monitoring by healthcare providers and follow up was scheduled according to the World Health Organization (WHO) recommended drug efficacy testing protocol. Whereas patients in the unsupervised group were instructed to take their medication at home without direct monitoring and were advised to adhere to the treatment regimen. Their medication adherence and malaria episodes were monitored through scheduled phone follow ups.