The aim of this study was to evaluate the usefulness of performing routine monthly bacteriological surveillance of the nursery environment, resuscitation equipment, baby placement sites, medications, formula feeds, cleansing solutions and miscellaneous medical items such as intravenous cannulae in relation to development of hospital-acquired bacteraemia in a Neonatal Intensive Care Unit (NICU) over a period of 19 months. The study is based on a retrospective review of records from the neonatal division and the microbiology laboratory. On discriminant analysis, only three NICU sites, namely baby placements, resuscitation equipment and various cleansing solutions were found to be significantly associated with hospital-acquired infections (HAI) (P < 0·001). The probability that a batch of newly admitted babies would develop HAI if all three sites were colonized was 0·602. Similarly, the probability if none of these sites was colonized was 0·10. On multiple logistic regression analysis, however, the relative risk of infection was greatest if baby placement sites were colonized (Odds ratio = 7·48; P < 0·01). In contrast, pathogens present in the inanimate NICU environment, e.g. floors, walls, sink-drains or furniture were not associated with HAI. Routine bacteriological surveillance of the inanimate nursery environment, is not therefore justified. However, our results suggest that routine bacteriological monitoring of medical equipment and cleansing solutions may have a role in the prevention of HAI. © 1991.