Although many studies have attempted to define levels of staff experience appropriate for the care of critically ill patients, minimal data is available on the effect of nursing staff inexperience (NSI) on the occurrence of incidents in the intensive care environment. The Australian Incident Monitoring Study in Intensive Care Units (AIMS-ICU), an anonymous, voluntary incident reporting system, can help to identify problems in which NSI may be implicated. NSI may be an incident in itself or contribute to the occurrence of other incidents. The objective of this paper was to identify incidents associated with NSI and estimate their effect on the quality of patient care. Incidents related to NSI were extracted from the AIMS-ICU database and analysed using descriptive methodology. Seven hundred and thirty five reports covering 1,472 incidents were identified as relating to NSI. Of these, 282 were described in the narrative section and 453 were selected as a contributing factor by the reporter. Major categories for the 1,472 incidents included airway and ventilation (317) drugs and therapeutics (468), procedures, lines and equipment (219), patient environment (234) and unit management (234). An undesirable major adverse patient outcome was selected in 20 per cent of reports. NSI associated incidents reported to AIMS-ICU suggest that NSI can have a negative impact on the quality of care delivered to critically ill patients as shown by the occurrence and outcome of incidents related to such inexperience. Errors are more likely to occur when NSI is combined with staff shortage, inadequate supervision and high unit activity. When rostering or employing staff, nurse managers and educators must consider the special requirements of inexperienced nurses. Safe patient care requires these issues be included in discussions about ICU resource allocation.