ABSTRACT.In a study of 124 hospital residents with a learning disability aged 60 years and over, DSM‐III‐R diagnostic criteria were used to determine the prevalence of dementia (12.9%), mood disorder (8.9%) and schizophrenia (6.5%). The figure for dementia confirms the prevalence given in previous studies, but the figures for mood disorder and schizophrenia are higher. It was found that mood disorder was commoner in the age group 60–69 years (P>0.01) and dementia was commoner in the age group 70–79 years (P>0.01). There were no significant differences in the prevalence of schizophrenia w