Over a 6-month period, 6 of 54 postthoracotomy patients developed pneu
monia and respiratory failure. Pneumonia was secondary to herpes simpl
ex virus type 1 in 3 of the 6 patients. Diagnostic efforts including b
ronchoscopy with bronchial washing, viral cultures, and cytologic exam
ination permitted early diagnosis and successful treatment with acyclo
vir. A high index of suspicion for herpes simplex pneumonia must be ma
intained in critically ill patients with undiagnosed pneumonia.