Summary An epidemic spread of Acinetobacter calcoaceticus var. anitratus in two neurosurgical wards is described retrospectively and prospectively using electronic data processing. Isolation of the species from sputum preceded the isolation from CSF by ½–1 year. Control measures directed against spread by air and indirect contact controlled the epidemic. Reexamination of 20 selected strains from the epidemic revealed two distinct resistance patterns.