In this retrospective study, we reviewed the patterns of use of the Edmonton Injector (EI) in 100 consecutive cancer patients. Seventy-eight patients used the EI for an average of 23 +/- 27 days. The main reasons for starting the EI were nausea (37 patients) and severe pain (31 patients). The median opioid dose equivalent to parenteral morphine (MEDD) was 264 +/- 443 mg/day. The mean duration of the subcutaneous injection site was 6.5 +/- 9.2 days. The most frequent reasons for change were accidental needle pulling (59%) and erythema (12%). Only two patients developed local infection (1% of 196 sites). The average cost of treatment was $1.65 Canadian per patient per day. No mechanical problems or refusals to start or continue treatment were detected. We conclude that the EI is a safe and simple device that allows for cost-effective parenteral administration of opioids for cancer pain.