We have modified the circuits of pressure-preset and volume-preset ventilators to permit the administration of ribavirin to mechanically ventilated infants suffering from respiratory syncytial virus. The modifications isolate the ventilator itself and permit continuous aerosolization for as long as seven days without ventilator malfunction from the effects of crystallized medication. Excessive spilling of ribavirin into the environment is also avoided. Each institution must devise its own experimental protocols and gain permission from its own committee on human experimentation and from the parent/guardian of the patient before administering such treatment.