BACKGROUND: A concise, accurate screening question for depression would be an important contribution to the Single Assessment Process for Older People. OBJECTIVE: To examine the performance of a previously validated screening question for depression, in a large community sample. METHODS: Both the single screening question, and the Geriatric Depression Scale (GDS-15) were completed by 13 670 people aged 75 and over in the community. Responses to the question were compared with a "standard" of scoring above different thresholds on the Geriatric Depression Scale (GDS-15). RESULTS: For more severe GDS-15 depression, the best performance of the question was a sensitivity of only 52% and a specificity of 93%. CONCLUSION: Even at its best, the question therefore misses almost half the cases. This highlights the problems of such simple approaches to routine screening.