Study design: Retrospective analysis. Objectives: To evaluate the e cacy of intrathecal baclofen (ITB) for upper extremity spastic hypertonia in tetraplegia of spinal origin. Setting: University of Alabama at Birmingham hospital. Methods: The medical records of 14 individuals with tetraplegia of spinal origin who underwent intrathecal baclofen pump placement were reviewed. The e ects of intrathecal baclofen on spasm frequency, deep tendon re¯exes, and tone (Ashworth scale) were assessed for the upper and lower extremities for a 1-year follow-up period.Results: There were statistically signi®cant declines in upper extremity spasm scores (1.8 points, P=0.012), re¯ex scores (1.4 points, P50.0001) and Ashworth scores (0.6 points, P50.0001) for the 1-year follow-up period. For the lower extremities, all decreases were signi®cant (P50.0001). There was also a statistically signi®cant (P50.0001) increase in intrathecal baclofen dosage requirements during the 1-year follow-up period to maintain the reductions in spasm frequency, re¯exes and tone. Conclusions: Intrathecal baclofen is a safe and e ective intervention for treating upper extremity hypertonia of spinal origin. In addition, the level of intrathecal catheter placement is felt to be of importance. Spinal Cord (2001) 39, 413 ± 419