We report these cases of high-frequency sensorineural hearing loss and tinnitus, following malaria prophylaxis with mefloquine (Lariam). Only one patient had partial remission of hearing loss after suspension of the treatment. In the remaining two cases the symptomatology remained unchanged. None of the patients reported improvement of tinnitus. Our experience suggests that a routine audiologic evaluation, before and after prophylactic use of antimalarial drugs, is important to monitor potential hearing deficit.