Day care at green care farms (GCFs) is a new care modality for community-dwelling older people with dementia. In view of the more physical and normal daily life activities available at GCFs than at RDCFs, we investigated whether functional decline differed between subjects from both day care settings. In this observational cohort study, primary caregivers of 47 subjects from GCFs and 41 subjects from RDCFs rated the subjects’ functional performance three times during one year. They also provided information on the subjects’ diseases and medication use. Generally, no significant change over time in functional performance, the number of diseases and the number of medications was observed, and no differences in these rates of change were found between subjects from both day care settings. This study suggests that GCFs are not more effective in maintaining functional performance or slowing down its decline in community-dwelling older people with dementia than RDCFs.