Purpose: This study evaluated the effectiveness of RSV-IGIV treatment by measuring the rate of RSV hospitalizations, complications of therapy, parents' acceptance of treatment, and treatment costs.Methods: This study was a prospective non-randomized evaluation of outcomes of a treatment group compared with a control group. The treatment group consisted of NICU graduates <32 weeks at birth and <6 months of age at the beginning of RSV season, or <2 years of age and treated for chronic lung disease within 6 months of the RSV season. The control group (52) included infants whose parents declined treatment (12), and 33-34 week GA NICU graduates (40). The treatment group received monthly outpatient RSV-IVIG infusions until 4/97. Evaluation included number of infusions, complications, number of inpatient days for respiratory infections, infusion costs and parents' acceptance of treatment. Results: Sixty-five eligible patients were identified; 17 enrolled in a concurrent study using intramuscular RSV monoclonal antibody, and 12 families declined treatment. RSV-IVIG infusions were initiated for the remaining 36 patients. Five patients did not complete the series; 3 received only 1 infusion because of insurance changes and 2 infants had adverse reactions and were not given further infusions. Thirty-one infants completed ≥3 infusions with no hospitalizations for respiratory illness; 4 of the control group required 7 hospitalizations for respiratory illness (p<0.05). In the treatment group, 4 infants were treated for bronchiolitis or RSV URI without inpatient therapy. Of the 13 infants requiring O2 at onset of RSV season, all weaned from supplemental O2 by 4/97 (the apparent peak of our RSV season). Complications of RSV-IGIV infusions occurred in 3 patients, without deaths in either group. Completion of the infusions and telephone surveys demonstrated parents' acceptance of the treatment. The costs of the RSV-IGIV infusions averaged $1240 per patient visit, for a total of $173,600 and compared favorably to projected costs from hospitalizations. Conclusions: RSV-IGIV infusions significantly decreased the rate of hospitalizations for respiratory illness in this high-risk group of infants. Complications were few, treatments were accepted by parents, and costs were comparable to projected inpatient charges. RSV-IGIV infusions appear to be feasible in an outpatient setting.