The results of intermittent GH treatment of 3-7 1/2 years duration in seven patients with isolated GH deficiency (IGHD) and five patients with multiple pituitary hormone deficiencies (MPHD) are presented. This therapeutic schedule was found to be comparably effective to those using a continuous-administration schedule. In contradistinction to the findings obtained with the latter, there was no progressive decline in growth velocity. The patients with IGHD were found to respond better than the patients with MPHD both in the first course as well as in consequent courses. In the intervals between courses, the growth velocity was less than in the pretreatment period in both groups. It is concluded that optimal results can be obtained by instituting an initial course of continuous treatment of 1 year's duration for the IGHD patients and of 2 years' duration for the MPHD patients, followed by an intermittent therapeutic schedule. This regime not only leads to the same growth achievement obtained with long-term continuous administration of GH but allows conservation of supplies of this very scarce hormone.