Background. Optimising retention of rural and remote primary healthcare (PHC) workers requires workforce planners to understand what constitutes a reasonable length of employment and how this varies. Currently, knowledge of retention patterns is limited and there is an absence of PHC workforce benchmarks that take account of differences in geographic context and profession.Methods. Three broad strategies were employed for proposing benchmarks for reasonable length of stay. They comprised: a comprehensive literature review of PHC workforce-retention indicators and benchmarks; secondary analysis of existing Australian PHC workforce datasets; and a postal survey of 108 rural and remote PHC services, identifying perceived and actual workforce-retention patterns of selected professional groups.Results. The literature review and secondary data analysis revealed little that was useful for establishing retention benchmarks. Analysis of primary data revealed differences in retention by geographic location and profession that took time to emerge and were not sustained indefinitely. Provisional benchmarks for reasonable length of employment were developed for health professional groups in both rural and remote settings.Conclusions. Workforce-retention benchmarks that differ according to geographic location and profession can be empirically derived, facilitating opportunities for managers to improve retention performance and reduce the high costs of staff replacement.What is known about the topic? Health services located in small rural and remote locations are likely to continue to experience workforce shortages and high costs of recruitment. Health workforce retention is therefore crucial. However, effective rural health workforce planning and use of strategies to maximise retention of existing health workers is hindered by inadequate knowledge about baseline employment-retention patterns. What does this paper add? Differences in health worker retention patterns by geographic location and profession are most evident after the first 6 months through until the end of the second year of employment. Health worker-retention benchmarks that differ according to geographic location and profession are proposed. What are the implications for practitioners? Benchmarking workforce retention in comparable health services can enable identification of best practice and the underpinning retention strategies. Workforce planners can use this, together with knowledge of baseline retention patterns and the high cost of staff replacement, to guide the design, timing and implementation of cost-neutral retention strategies.