INTRODUCTION: The use of intrathecal morphine via a morphine drug delivery system has been shown as a promising alternative to the treatment of chronic pain. These programmable devices can deliver morphine via simple or flexible programs. Simple programs release morphine continuously at the same rate over a 24-hour period, whereas flexible programs are optimized to release different dosages at different times. METHODS: Patients were enrolled at St. James Mercy Hospital, University of Rochester, New York from February 2016 to February 2020. An out-patient intrathecal morphine trial was performed by injecting a single dose of 0.1-0.3 mg of preservative free morphine in the lumbar intrathecal space. Following at least 60% reduction in pain compared to baseline, a permanent intrathecal catheter and morphine pump were implanted. The drug delivery system was programmed to deliver morphine doses in a simple continuous or flexible mode. Follow up visits occurred between 12 and 60 months, and the efficacy of the flexible dosing was assessed. RESULTS: 58 patients enrolled (34 female, 24 male, median age 59), 46 patients were on flexible dose morphine and 12 were on simple dose morphine. Statistical analysis found a significant difference in pain reduction between the two groups (p < 0.01). The flexible sample had a mean reduction in pain of 8.72 and the simple sample had a mean reduction in pain of 8.17 out of 10 points on the 0-10 pain scale. There were no infections or complications present in the study. CONCLUSION: While both flexible and simple program intrathecal morphine drug delivery system proved effective in reducing chronic pain, flexible programs were significantly more effective. A future multi-center study with a larger sample size is desired.