We have addressed the safety of alum-adsorbed BBG2Na, a recombinant respiratory syncytial virus (RSV) subunit vaccine, in infant macaques. Animals received two vaccinations, and were challenged 4 months later with RSV. In two of four BBG2Na-vaccinated animals, specific IL-13 producing T cells were detected. Upon challenge, low level pulmonary eosinophilia was observed in the same two animals. Although the levels of these responses were substantially lower than those observed in the FI-RSV controls, these data suggest that more extensive studies focusing on immunopathological safety of alum-adsorbed BBG2Na in non-human primates would be required before proceeding to clinical trials in seronegative infants.