OBJECTIVE: The purpose of this pilot study was to determine the feasibility of using mechanical measures of stretch reflexes to monitor spasticity after intrathecal baclofen dosage changes. DESIGN: Mechanical measures were made in studying six participants with cerebral palsy who were undergoing treatment for spasticity using intrathecal baclofen therapy. Mechanical measurements of stretch reflexes were made before and after pump implant in four of the six participants and after dosage changes in all participants, for a period of up to 2 yrs. The measurements comprised electromyograms and resistive torque responses to movement of the ankle, imposed with an isokinetic dynamometer. For each test session, random movements were applied to the ankle at each of four to seven speeds, repeated three or five times. RESULTS: Stretch reflex excitability decreased in three of four participants after initiation of intrathecal baclofen therapy and decreased with increasing dosages in three of the six participants. Broken catheters coincided with heightened mechanical measures in two cases. CONCLUSION: Mechanical measures of stretch reflexes change after intrathecal baclofen dosage adjustments, reflecting the clinical course of intrathecal baclofen therapy.