Ireland had the highest incidence of prostate cancer in Europe in 2008, due to widespread prostate specific antigen (PSA) testing.To investigate practices and costs of PSA testing in Ireland, 2008-2010.Postal laboratory questionnaire. Results were compared with 2006 and 2007 surveys.Response rate was 95 % (42/44). In 2010, 37 laboratories measured total PSA (tPSA); 10 measured free PSA (fPSA). Eight assays were used and cut-offs to define 'normal' tPSA varied widely. There was a 9.9 % annual increase in the number of tPSA tests and a -31 % annual decrease in the number of fPSA, 2006-2010. A 100-fold difference in tPSA workload was observed across laboratories. In 2010, the estimated cost of PSA testing was a,not sign3,649,984 (95 % CI a,not sign2,532,745-a,not sign4,767,222).Health service costs of PSA testing are significant. The number of tPSA tests continues to rise; fPSA use fell by almost one-third. Inter-laboratory variation in testing practices persists. These have potentially important clinical consequences for men and need to be addressed.