OBJECTIVES: To examine whether leisure activities can alleviate depressive symptoms among nursing home residents with very mild to mild dementia. METHODS: A cluster-randomized open-label controlled design. Thirty-six residents with at least moderate depressive symptoms were randomized by home into three conditions-mahjong (a.k.a. mah-jongg), tai chi, and handicrafts (placebo). Activities were conducted three times weekly for 12 weeks. Outcome measure was Geriatric Depression Scale (GDS) administered at baseline, posttreatment, and at 6 months. RESULTS: Repeated-measures analysis of variance showed a group by time interaction on the GDS. Unlike control and tai chi participants whose scores remained relatively unchanged, the mahjong group reported a drop of 3.25 points (95% confidence interval: 1.00-5.50) on the GDS at posttreatment but gained back 2.83 points (95% confidence interval: 1.95-5.47) at 6 months. Activity discontinuation might be the reason for depression to return to baseline. CONCLUSIONS: Mahjong can lower depressive symptoms in those with mild dementia, but activity maintenance may be essential for long-term effects.