The HAM-D was designed to measure the severity of depressive symptoms in patients with primary depressive illness, and is the most commonly used observer-rated depressive symptom rating scale. It is used for quantifying the results of an interview and its value depends entirely on the skill of the interviewer in eliciting the necessary information. The HAM-D is useful for monitoring changes in depressive symptoms with treatment and in comparing the efficacy of various interventions if the patient requires more than one type of treatment. The scale contains 17 variables measured on either a five-point or a three-point rating scale, the latter being used where quantification of the variable is either difficult or impossible. Among the variables are: depressed mood, suicide, work and loss of interest, retardation, agitation, gastrointestinal symptoms, general somatic symptoms, hypochondriasis, loss of insight, and loss of weight. It is useful to have two raters independently scoring a patient at the same interview. The scores of the patient are obtained by summing the scores of the two physicians. The reliability and validity are generally favorable. Completion time is 15-20 minutes.