To confirm reports that chloroquine-induced pruritus might have a negative impact on chloroquine utilization on malaria control in Dar es Salaam, a precoded questionnaire was administered to 300 malaria patients and the respondents were then followed up at their homes during the period of their malaria treatment. It was found that 45% of the study population had suffered from chloroquine-induced pruritus at some time in their life and 27% complained of it during the study. Chloroquine-induced pruritus was found to have a significant negative impact on chloroquine utilization on malaria control in Dar es Salaam, Tanzania (P less than 0.001). The defaulting rate attributable to chloroquine-induced pruritus was 64%. The high defaulting rate (91%) among the patients with chloroquine-induced pruritus is suspected to be among the factors that contribute to the emergence and spread of resistant malaria parasites in Dar es Salaam. However, studies are needed to confirm this point. Studies are also needed to determine if there may be familial predisposition to chloroquine-induced pruritus as hypothesized in this study.