The development of a long-acting or depot preparation of growth hormone-releasing hormone (GHRH) may have many advantages over conventional treatment (with GH) of GH-deficient children. Pyridostigmine, an acetylcholinesterase inhibitor, has been shown to augment basal GH secretion and the GH response to GHRH in short children. It may thus provide adjuvant therapy to depot GHRH. The GH response to a nocturnal subcutaneous infusion of GHRH (1-29)NH2 in doses of 5 and 10 micrograms/kg/hour was investigated in five short, slowly growing children. The effect of oral pyridostigmine 60 mg on nocturnal GH secretion and the GH response to a nocturnal infusion was also examined. The subcutaneous infusion of GHRH augmented pulsatile GH release in all five children. There was a dose-related response to subcutaneous GHRH for the GH area under the curve and mean GH pulse amplitude, but no change in the number of pulses. There was a significant rise in the mean baseline GH concentration during the GHRH infusion compared with placebo. Pyridostigmine had no effect on either basal or stimulated GH secretion.