Adults with growth hormone deficiency (GHD) experience poor quality of life that can be expressed as feelings of fatigue, social isolation, emotional distress, depression, sleep disturbances, reduced physical mobility, and an impaired sense of well-being. These effects negatively affect the patient's ability to perform tasks related to work and leisure and, subsequently, impose costs on society in terms of lost work time, payment of unemployment benefits, and early retirement. Adults with GHD who are treated with growth hormone (GH)-replacement therapy experience improvements in various aspects of their quality of life. These improvements can be sustained over long periods with GH-replacement therapy. Future studies of quality of life in adults with GHD likely will employ disease-specific, validated quality-of-life instruments and will explore in greater detail the mechanisms responsible for the detrimental effect of GHD on quality of life.