Erythromycin resistance was analyzed in 280,415 Danish Staphylococcus aureus strains isolated from hospitalized patients and phage-typed in the period 1967 to 1987. Multiresistant, erythromycin-resistant strains decreased during the whole period, while strains resistant only to penicillin and erythromycin increased after 1972. This increase coincided with an increase in erythromycin consumption in Denmark from 0.4 DDD/1000 persons/day in 1978 to 1.9, in 1987. Erythromycin consumption in nine large Danish hospitals was significantly associated with the level of erythromycin-resistant S. aureus at the hospitals.