Intermittent preventive treatment with sulfadoxine/pyrimethamine (SP) is recommended for malaria prevention in infants (IPTi-SP). Serious adverse events, including Stevens-Johnson syndrome (SJS), have been reported following exposure to SP, but few infant-specific data exist. The safety of IPTi-SP was evaluated as part of a pilot implementation programme in southern Tanzania using three methods: spontaneous adverse event reporting to capture suspected adverse drug reactions (ADR); a census survey documenting rash-related hospital admissions among children < 2 years of age; and verbal autopsies (VA) completed for rash-related deaths in 2-11-month-olds. Approximately 82 000 IPTi-SP doses were administered to approximately 29 000 children. In total, 119 suspected ADRs were reported, 13 in children aged <2 years, only one of whom had received IPTi-SP. The census involved 243 612 households. Only one rash-related admission was reported amongst 1292 children aged 2-11 months, but this child had no history of exposure to SP. Moreover, 30 of 699 deaths in 2-11-month-olds were said to have been associated with a skin rash. The rates of rash-associated death were 0.59/1000 person-years at risk (PYAR) and 1.17/1000 PYAR in intervention and comparison areas, respectively (P = 0.79). VAs did not suggest SJS or any other ADR. We conclude that IPTi-SP is associated with a very low incidence of severe skin reactions. [ClinicalTrials.gov identifier: NCT00152204].