The recent data concerning antibiotic resistance of the enterobacteria isolated in Greek hospitals are reviewed. A variety of mechanisms of resistance, clustered in most of the cases, was observed. Epidemics of plasmids were responsible for dissemination of third-generation cephalosporins, aminoglycosides, and trimethoprim resistance among Klebsiella pneumoniae and, to a lesser extent, Escherichia coli isolates. Stable depression of the expression of chromosomal cephalosporinase is the main cause of resistance to third-generation cephalosporins observed at high frequencies in Enterobacter spp. strains.