In this study, 50 patients received an initial bolus epidural injection of 2 mg morphine–hydrochloride followed by a continuous-plus-on-demand epidural infusion of a 0.25% morphine-hydrochloride solution by means of a small, externally worn infusion device, for constant pain relief after abdominal operations. Mean morphine consumption on the operation day (until 8:00 AM on the first postoperative day) was 4.8 · 0.2 mg, on the first postoperative day (until 8:00 AM on the second postoperative day) 1.9 · 0.2 mg, and on a second postoperative day until 8:00 PM, 0.6 · 0.1 mg. The mean morphine consumption over 50 h was 7.1 · 0.3 mg; in the first 25 h and in the following 25 h after the operation, 5.44 · 0.3 mg and the significantly lower amount of 1.64 · 0.2 mg morphine, respectively, were consumed (P< 0.001). There were no serious side effects. Serum levels of free, unmetabolized morphine immunoreactivity decreased during the treatment. The described method is recommended for treating postoperative pain, as it offers constant analgesia and the possibility of individualized treatment.