1. During a long-term follow-up study of patients previously hospitalized with Sydenham's chorea, a high incidence of psychological disturbance was encountered prior to the onset of chorea, and at the time of current evaluation, an average of 29 years later.
2. Seventy-five per cent of patients with Sydenham's chorea were currently found to manifest evidence of psychiatric disturbance.
3. A control population similarly evaluated showed a 25% incidence of psychiatric disability—about the expected incidence for the general population.
4. This study emphasizes the need to consider psychological factors as part of the total evaluation of patients with Sydenham's chorea.