METHOD: All 2035 Asian (88% Chinese, 7% Malays and 5% Indonesians) psychiatric in-patients in the state psychiatric hospital in Singapore were surveyed for occurrence of oculogyric spasm (OGS) over a two-month period.

RESULTS: Thirty-four patients (1.7%) developed OGS (53% male and 47% female). All the 34 patients had been on maintenance antipsychotic drugs for more than five months. Eighteen patients had recurrent attacks. The mean chlorpromazine equivalent daily dose for those patients with recurrent OGS was 511 mg. This was significantly higher (P < 0.05) than the 277 mg daily dose received by those without recurrent OGS. Most (68%) of the attacks occurred between 1400-2000 h suggesting that OGS may have a diurnal variation.