The efficiency of an established iron-supplementation program for pregnant women in Jakarta, Indonesia was investigated. Hemoglobin, serum ferritin, and packed cell volume (PCV) were measured at the start of the study and after 2 mo supplementation with 300 mg ferrous sulphate/d. The women (n = 45) were questioned about compliance and stool samples were checked for iron content to control for tablet intake. Twelve women dropped out. Prevalence of anemia (42%) did not decrease during the study period. Of the remaining 33 women, 64% (n = 21) claimed to have taken all iron tablets. This was only confirmed by positive stool tests in 12 women. Serum ferritin and PCV increased in women with positive stool tests (P < 0.05 and P < 0.01, respectively) after supplementation. It is concluded that compliance was low and that the iron dose needs to be increased. Supplementation programs need reliable monitoring and evaluation systems.