Determination of national nuclear medicine technologist workforce size was made from census data in 2001 and 1996 and from the professional body in 2004. A survey conducted by the authors in 2005 provided retention patterns in north-eastern Australia and suggested causes. Utilisation of nuclear medicine diagnostic services was established through the Medicare Benefits Schedule group statistics. More than half the nuclear medicine technologist workforce is under 35 years of age. Attrition commences from age 30, with very few workers over 55 years. In 2005 there was a 12% attrition of the survey workforce. In the past decade, service provision increased while workforce size decreased and the nuclear medicine technologist workforce is at risk of failing to meet the anticipated rise in health service needs.