Background: Depression in men diagnosed with prostate cancer is associated with several adverse outcomes. However, some data suggest that standard methods of assessing depression in males via the criteria for Major Depressive Disorder (MDD) may omit several extra key symptoms of male depression. Therefore, this study tested the comparative effects of standard MDD-based diagnostic criteria for depression and criteria for 'male depression' in a sample of men diagnosed with prostate cancer. Method: 191 men diagnosed with prostate cancer completed a postal survey questionnaire containing questions about background variables, the Patient Health Questionnaire-9 for depression (PHQ9) and the Gotland Male Depression Scale (GMDS). Comparisons were made of the relative prevalence of depression according to these scales, plus a scale that combined the PHQ9 and GMDS extra items for male depression Results: Although there were significant correlations between total PHQ9 and GMDS scores, over one-third of variance in the GMDS was not accounted for by the PHQ9, and sensitivity of the PHQ9 against the GMDS showed that about 24% of those patients identified as depressed on the GMDS would not be similarly identified on the PHQ9. Different prevalence rates from the two scales suggested that they were assessing different sets of symptoms of depression. A combined PHQ9-GMDS scale of 15 items was used to produce a profile of male depression in these patients. Conclusion: Adequate and reliable assessment of depression in men diagnosed with prostate cancer may require use of additional symptoms to those listed for MDD, and treatment planning and delivery could be more precise and effective using this methodology.