OBJECTIVES: To investigate whether the improved well-being and quality of life (QoL) and decreased use of healthcare resources seen during the first year of GH substitution therapy in GH-deficient adults are maintained over subsequent years of treatment. METHODS: Data were analysed from 237 Swedish hypopituitary adults with GH deficiency (GHD) who had received 2 (n=196) or 3 (n=130) years of GH replacement therapy (mean dose, 0.43 mg/day). All patients (117 men, 120 women; mean age at baseline, 51.5 years; range, 35-69 years; 141 (60%) with at least three additional hormone deficiencies, and 16 with isolated GHD) were included in KIMS (Pharmacia International Metabolic Database) - a pharmacoepidemiological survey of adults with GHD. None had previously received GH replacement in childhood. Eighty-five (36%) had had <10 years of formal education; 142 (60%) were in full or part-time work, and 39 (17%) had taken early retirement or were receiving a disability pension. QoL was assessed using AGHDA - a disease-specific questionnaire - and the generic PGWB index. Information on the patients' social situation and well-being was obtained from a patient life situation form. Statistical analysis was by repeated measurements regression. RESULTS: A significant subjective improvement in well-being was noted by 78% of patients after 1 year and by 86% after 3 years. QoL (both AGHDA and PGWB) showed statistically significant improvements after 1 year, which were sustained for up to 3 years. The VAS score for leisure-time activity also increased significantly during the whole follow-up period, as did patients' satisfaction with their level of physical activity. Use of healthcare resources (days of reported sick-leave and doctor visits) decreased significantly during the first year of treatment. CONCLUSIONS: Three years of GH treatment in adults with GHD has a sustained positive effect on well-being, QoL and physical activity, and decreases the consumption of healthcare resources.