OBJECTIVE To determine the source of Burkholderia cepacia complex associated with a hospital outbreak and describe the measures taken to identify and confirm the source. METHODS A 250-bed, tertiary care pediatric hospital in Denver, Colorado. METHODS An epidemiologic investigation was used to identify possible causes for an apparent outbreak of B. cepacia complex in pediatric patients who had new positive cultures with this organism from December 2003 to February 2004. Chart review, microbiology reports, surgical records, site visits, literature review, staff interviews, and cultures of common products and equipment were performed to determine a source of contamination. Random amplified polymorphic DNA and pulsed-field gel electrophoresis typing, performed by 2 independent laboratories, were used for molecular typing of patient and source isolates. RESULTS Five pediatric patients had new positive B. cepacia complex cultures from either the sinus or the respiratory tract, and all 5 patients had prior exposure to 0.05% oxymetazoline hydrochloride Major Twice-A-Day 12-hour nasal spray (Proforma, Miami, FL). Four of the 5 patients had isolates that were identical to the B. cepacia complex isolates recovered from the unopened Twice-A-Day 12-hour nasal spray. CONCLUSIONS Intrinsic contamination of Major Twice-A-Day 12-hour nasal spray with B. cepacia complex resulted in nosocomial transmission to 4 patients at our facility and resulted in a voluntary product recall by the manufacturer. B. cepacia complex species are common contaminants of an increasing variety of nonsterile medical products. Enhanced culture techniques may be useful in evaluating possible product contamination, suggesting additional measures that should be considered to assure the safety of products that may be used in high-risk patients.