Forty-five patients with parkinsonism were carefully matched for age and sex with 45 chronically disabled control patients with a significantly more severe grade of physical handicap. Depression was measured by the Hamilton Rating Scale, and it was found that the parkinsonian group was very significantly more depressed than the control group (p less than 0-0001). Depression scores in both groups were unaffected by the patients's sex or by the severity of the disability. Analysis of the individual ratings of the Hamilton Scale showed that parkinsonian patients had significantly higher scores on items relating to suicide, work and interests, retardation, psychic anxiety, general somatic symptoms, and loss of insight. It was concluded that patients with parkinsonism suffer a degree of depression which cannot be solely a reaction to the stress of physical disability. This finding is discussed with reference to the monoamine hypothesis of depressive illness.