Abstract Background Relapses in vivax malaria have posed great challenges for malaria control, and they also account for a great proportion of reported cases. Knowing the real effectiveness of a 7-day primaquine (PQ) scheme is crucial in order to evaluate not only the cost-effectiveness of implementing new anti-hypnozoite drugs, but also how health education strategies can guarantee better compliance and be reinforced. This study aimed to evaluate the effect of daily treatment with chloroquine and PQ supervised by health workers versus prescription without supervision. Methods The outcome was the passive detection of new positive thick blood smears up to 180 days, based on the official data records from the National Malaria Control Programme. The recurrences seen in the real life were, therefore, used as a surrogate for true relapses. Results Patients under supervised treatment had a lower risk of recurrence up to day 180 when compared to the unsupervised treatment (17.9% vs. 36.1%; p = 0.027). Conclusions The lack of supervision in the non-supervised group (which followed standard of care in the real life) enabled proper comparison, as consent itself would have lead to greater compliance in this group. Future studies should scale such an analysis to different settings in the Brazilian Amazon.