Background Nursing homes are increasingly introducing electronic health record (EHR) systems into nursing practice; however, there is limited evidence about the effect of these systems on nursing staff time. Aims To investigate the effect of introducing an EHR system on time spent on activities by nursing staff in a nursing home. Method An observational work sampling study was undertaken with nursing staff between 2009 and 2011 at two months before, and at 3, 6, 12, and 23 months after implementation of an EHR system at an Australian nursing home. An observer used pre-determined tasks to record activities of the nursing staff at nine-minute intervals. Results There was no significant change in registered nurses and endorsed enrolled nurses' time on most activities after implementation. Personal carers' time on oral-communication reduced, and time on documentation increased at most measurement periods in the first 12 months after implementation. At 23 months, time on these activities had returned to pre-implementation levels. Nursing staff time on direct care remained stable after implementation. No considerable change was observed in time spent on other activities after implementation. Conclusion Findings suggest that successful introduction of an EHR system in a nursing home may not interfere with nursing staff time on direct care duties. However, there is scope for improving the support provided by EHR systems through incorporation of functions to support collaborative nursing care.