In a prospective open study we tested the Edmonton injector (EI), a device designed by our group for subcutaneous injection of narcotics. In 25 patients, the EI was used for patient-controlled analgesia (PCA); mean duration of treatment was 28 +/- 10 days. Mean equivalent daily dose of morphine was 160 +/- 85 mg. All patients found the EI safe and simple to operate. The main reason for discontinuation was death (10 cases) or return to oral narcotics (8 cases). In 20 patients who were admitted to the hospital and were too ill to learn PCA, the EI was used for regular s.c. administration by nurses. Narcotics were administered every 4 h and extra doses were administered on a 'PRN' basis. Waiting time for a 'PRN' dose in 8 patients before starting the EI was 18 +/- 7 min; after the EI was started, it was 3 +/- 4 min (P less than 0.01). We conclude that the EI is safe, effective and inexpensive, and that it will be particularly useful in smaller hospitals and developing countries.