Immunocompromised patients are vulnerable to severe infections due to respiratory syncytial virus (RSV) and parainfluenza viruses (PIV), and therefore prevention and treatment strategies must be considered. The prevention of RSV disease with high-titer RSV-specific immune globulin has been documented in very young children but has not been systematically studied in high-risk adults. Vaccines against RSV and PIV are under development, but their use in immunocompromised patients is problematic. Ribavirin aerosol therapy is licensed for the treatment of RSV in pediatric patients and has also been used to treat RSV disease in adults and PIV disease in severely immunocompromised children and adults. Uncontrolled trials show that early therapy with ribavirin aerosol may be beneficial, but treatment of pneumonia in patients with respiratory failure is rarely successful. Other potential treatments for RSV or PIV disease include high-dose, short-duration ribavirin therapy; combined immunoglobulin and ribavirin therapy; polyclonal and monoclonal antibodies; and, potentially, immunomodulators.