In a retrospective analysis, we identified 38 evaluable patients who received intravenous ribavirin after adenovirus or RSV detection in the respiratory and/or gastrointestinal tract throughout the years 1998 and 2001. A total of 43 treatment cycles are analyzed. Intravenous ribavirin was combined with cidofovir in about half of the patients. In six out of eight patients treated because of RSV isolates from the respiratory tract, the virus was no longer detectable after treatment. In case of adenovirus isolates, the treatment was efficacious in eradicating the virus from the respiratory tract in more than 60% and from the gastrointestinal tract in 75% of treatment cycles. The addition of cidofovir was not beneficial in eradicating RSV isolates, but somewhat improved the virus clearance of adenovirus. Virus clearance was associated with a trend to a better median survival after virus detection. There were some episodes of suspected hemolysis and a trend towards lower leukocyte counts, reaching grade 3 toxicity in about 15% of treatment cycles. However, in general, intravenous ribavirin was well tolerated. In conclusion, the possible efficacy of intravenous Ribavirin in controlling RSV or adenovirus infections after allogeneic stem cell transplantations should be evaluated in prospective clinical trials.