Blink rates were measured in 25 patients with fluctuating Parkinson's disease in the "off' and "on" periods. In 17 patients, the "off"-period blink rate was low and increased after administration of levodopa. In the remaining eight patients, the "off"-period blink rate was high and returned to normal levels after levodopa. It is suggested that increased blink rate in the latter group represents a new form of "off"-period dystonia.