A randomized, double-blind, placebo-controlled trial was conducted with 40 fibromyalgia patients. The purpose was to determine the benefit of nabilone in pain management and quality of life improvement in these patients. After a baseline assessment, the treatment group was titrated up on nabilone, from 0.5 mg PO at bedtime to 1 mg BID over 4 weeks. At the 2 and 4 week visits, the primary outcome measures: Visual analogue scale (VAS) for pain, the number of tender points, the average tender point pain threshold, and the Fibromyalgia Impact Questionaire (FIQ) were evaluated. Patients in the control group received a placebo. Following a 4 week washout period, patients returned for a reassessment of the primary outcome measures. There were no significant differences in population demographics between the two groups at baseline. There was a significant decrease in the VAS (mean difference 2.04, p<0.02), improvement in function on the FIQ (mean difference 12.07, p<0.02), and decrease in anxiety (mean difference 1.67, p<0.02), in the nabilone treated group at 4 weeks. There was no significant improvement in the outcome measures in the placebo group. The nabilone treated group had a significant increase in side effects per person at 2 and 4 weeks of treatment (mean difference 1.58, p<0.02 and 1.54, p<0.05 respectively. Nabilone appears to be a reasonable, well tolerated, treatment option in patients with fibromyalgia, with significant benefits in pain relief and functional improvement.