The 2008 financial crisis exacerbated an already mounting workforce challenge faced by most health services in the western world, namely the recruitment and retention of qualified nurses. This paper examines two additional challenges of relevance to workforce planning in health care, an ageing nursing workforce and reliance upon migrant nurses to solve short-term workforce issues. Using Ireland as a case exemplar of these issues, this paper argues that policy makers and service providers should seek not only to address the challenge of retaining trained newly qualified and younger nurses but also focus on supporting older nurses and migrant nurses to remain within the workforce. The findings of this paper highlight the need for workforce planners, policy makers and service providers to take account of an ageing nursing workforce and reliance on foreign-trained nurses as a solution to short-term planning difficulties. Failure to address this need is likely to lead to significant workforce difficulties for health services into the future and undermine current efforts to increase the number and long-term retention of qualified nursing staff. Policy makers and service providers should focus on the retention of trained older nurses as an important element of workforce planning. © 2018 International Council of Nurses.