The effectiveness of prophylaxis with cotrimoxazole against placental and infants’ malaria parasitaemia, anaemia and birth weight was assessed among HIV-infected pregnant women in Jos. Thick and thin blood smears of placental and cord blood were examined for malaria parasitaemia while other birth outcomes were taken at delivery. Out of the 135 HIV-infected pregnant women exposed to cotrimoxazole (CTX) Group A and 100 to sulfadoxine-pyrimethamine (SP) Group B for prophylaxis, 102(75.6%) and 93(93.0%) in groups A and B respectively were followed-up to delivery. Three (2.94%) infants in group A and 1 (0.98%) in group B were preterm deliveries/stillbirths. No maternal death was recorded throughout the study. Placental malaria was 5.9% among group A and 7.5% among group B. No malaria parasites were detected in the cord blood of group A infants while 3.2% of group B infants were infected with the parasites. Mean placental malaria parasitaemia was low (<2000asp/μl) throughout the study, with 1266.6 and 0 asp/μl in the placenta and cord blood respectively of Group A and 1157.14 and 933.3 asp/μl respectively, in group B. Severe infants’ anaemia (PCV<25), was higher among study population who took SP for prophylaxis compared to those who took CTX 8(8.60%) and 6(5.90%) respectively. The means of all other birth outcomes were within normal ranges except for the placental and cord blood PCVs which were slightly lower than the normal ranges (36-47% and 42-60% respectively). Low birth weight (LBW) was observed among infants in SP group (B) than CTX group (A). Placental malaria was significantly associated with cord blood malaria, infant birth weight, and cord blood PCV. Prophylaxis with CTX effectively reduced placental and infants’ malaria parasitaemia compared to the standard SP. Continuous monitoring of haemoglobin status of HIV-infected pregnant women with low CD4+ count should be strengthened for promptly treatment of anaemic patients.