We have previously shown high rates of co-infection with Respiratory Syncytial Virus (RSV) and human Metapneumovirus (hMPV) in infants with severe bronchiolitis at our institution in 2000–2002, and that co-infection was associated with increased disease severity. In this study, we have attempted to identify differences in intubated infants with severe RSV infection with and without hMPV co-infection. Here we show that RSV+/hMPV+ were clinically symptomatic for longer than RSV+/hMPV− infants, but that no differences in airway total cell concentration, differential cell count or cytokine/chemokine concentrations were detectable. Pediatr Pulmonol. 2007; 42:740–743. © 2007 Wiley-Liss, Inc.