Continuing and worsening nurse shortages nationally and internationally have reignited the debate in Australia about the methods of measuring nursing workload. As workload is one of the most significant factors in nursing retention, measuring nursing workload reliably is the critical initial step to understanding the relationship between workload, nursing retention and patient safety. In Australia, some states and territories have no measure of nursing workload and those states that have introduced measurement methods are inconsistent in their approach. This paper provides a critical review of the methods of measuring nursing workload with particular reference to Australia. It also explores the strengths and limitations of each approach in terms of its reliability and utility. This review highlights the implications of not understanding fully the impact of excessive workload on patient and nurse safety outcomes.