The type, frequency, and antimicrobial sensitivity pattern of bacteria were studied at Nemazee Hospital in Shiraz, Iran, during 1981, 1985, and 1987. The study revealed changes of potential pathogens in all three respects during the 8-year period spanned. Gram-negative bacteria remain the most common cause of important infections, and Staphylococcus aureus is the most frequent gram-positive isolate. Factors leading to increasing prevalence of drug-resistant organisms must be identified and proper action taken to combat this problem.