With use of a randomized study design, quality of life (QOL) and physical symptoms of opioid addicts at admission were compared with slow-release oral morphine, methadone, and sublingual buprenorphine maintenance program participants after 6 months of treatment. The study was conducted from February to July 2004 in the outpatient drug user treatment center at University Department of Psychiatry at Innsbruck, providing maintenance treatment programs and detoxification in Tyrol, Austria. One hundred twenty opioid users seeking treatment were compared with 120 opioid-dependent patients retained for 6 months on a slow-release oral morphine, methadone, or sublingual buprenorphine maintenance program. The German version ("Berlin Quality of Life Profile") of the Lancashire Quality of Life Profile was used, and illicit opioid use was determined by urinalysis. Physical symptoms were measured by using the Opioid Withdrawal Scale. Urinalyses revealed a significantly lower consumption of cocaine and opioids in all three substitution groups than in patients at admission (p < 0.001 and p < or = 0.004, respectively). Both the buprenorphine and the methadone maintenance group showed significantly more favorable values than opioid clients at admission for stomach cramps (p < or = 0.002), muscular tension (p < or = 0.027), general pain (p < or = 0.001), feelings of coldness (p < or = 0.000), heart pounding (p < or = 0.008), runny eyes (p < or = 0.047), and aggressions (p < or = 0.009). Patients who received slow-release oral morphine treatment generally showed the least favorable QOL scores compared with patients at admission or sublingual buprenorphine and methadone clients. Patients in the sublingual buprenorphine or methadone program showed nearly the same QOL scores. The buprenorphine and the methadone maintenance group showed significantly more favorable values than opioid clients at admission regarding leisure time (p < or = 0.019), finances (p < or = 0.014), mental health (p < or = 0.010), and overall satisfaction (p < or = 0.010). Slow-release oral morphine is a well-established treatment for pain, but more research is required to evaluate it as a treatment for heroin dependence. The present data indicate that slow-release oral morphine could have some disadvantages compared with sublingual buprenorphine and methadone in QOL, physical symptoms, and additional consumption. The results further suggest that buprenorphine treatment is as effective as methadone in effects on quality of life and physical symptoms.