Objectives The effect of retirement on mental health is not well understood. We examined the prevalence of hospital treatment for depression and purchase of antidepressant medication before, during and after retirement in a Danish population sample. We hypothesised that retirement was followed by reduced prevalence of hospital treatment for depression and antidepressant purchase.

Methods Participants were 245 082 Danish workers who retired between 2000 and 2006. Information on retirement, hospital treatment and antidepressant purchases were obtained from Danish national registers. The yearly prevalence of hospital treatment for depression and antidepressant purchases was estimated in relation to the year of retirement from 5 years prior to the retirement year to 5 years after retirement. Using logistic regressions with generalised estimating equations we analysed the trends in prevalence before, during and after the retirement.

Results Two of 1000 participants were hospitalised with depression in the year of their retirement and 63 of 1000 purchased antidepressant medication during the retirement year. The prevalence of hospital treatment for depression increased before and around retirement, followed by a slight decline from 2 years after retirement with the prevalence of hospitalisation dropping from 0.21%(retirement +2 years) to 0.16% (retirement +5 years). For antidepressants, we observed a steady increase in purchases before retirement (retirement −2 years). This increase levelled off in the years around retirement, but continued after retirement (retirement +2 years).

Conclusions Overall, this study did not confirm the hypothesis that retirement is beneficial for mental health measured by hospitalisation with depression and treatment with antidepressants. Although the temporary levelling off of the increase in antidepressant treatment around time of retirement might indicate a beneficial effect, this possible effect was only short-term.