Patients with chronic spinal cord injury (SCI), a condition associated with reduced physical function, have been reported to have lower plasma insulin-like growth factor-I (IGF-I) levels than able-bodied persons. We evaluated the potential for daily low-dose baclofen administered over several weeks to increase plasma IGF-I levels. Ten healthy male outpatients with chronic SCI were studied prospectively. Patients received escalating doses of baclofen for 4 weeks at each dose level (5, 10, and 20 mg/d). At each dose of baclofen, an increase in the plasma IGF-I was noted; significant increases in plasma IGF-I occurred at 2 weeks after administration of drug at doses of 10 and 20 mg/d, with a subsequent rise to peak levels on baclofen 20 mg/d [baseline, 205+/-74; peak, 218+/-76 (not significant), 239+/-83 (P<.05), 263+/-87 microg/L (P<.05), at baclofen 5, 10, and 20 mg/d, respectively]. In conclusion, low-dose baclofen administration for 4 weeks stimulated the growth hormone-IGF-I axis in persons with SCI, with the potential for beneficial effects on body composition.