OBJECT The objectives of this multicenter study were to monitor the performance of a 10-ml pump infusing intrathecal baclofen to treat 100 children with cerebral spasticity, to monitor complications associated with the pump, and to correlate pump-related complications with body habitus. METHODS Age at implantation of the pump ranged from 1.4 to 16.8 years (mean 8.1 years). The effects of ITB on spasticity in the upper and lower extremities were evaluated using the Ashworth Scale. Data were collected regarding implant site, infection, complication, and body mass index (BMI). Ashworth Scale scores decreased significantly in the upper and lower extremities at 6 and 12 months after pump implantation (p < 0.001). There were four serious system-related complications, all specific to catheters. There were 32 serious procedure-related complications in 21 patients: 11 complications were infections that occurred in nine patients. Four of nine pump-induced infections were treated with pump removal and antibiotic therapy; five infections were treated successfully with antibiotic therapy alone, without pump removal. In children younger than 8 years of age there was a significantly higher incidence of serious procedure-related adverse events than in older children. There was no significant correlation between BMI and the incidence of pump pocket-related complications or infections. CONCLUSIONS The 10-ml pump can be used therapeutically in small children, particularly those weighing less than 40 lbs, with greater ease and less wound tension, than the conventional 18-ml pump. The incidence of complications associated with the 10-ml pump in younger children appears to be similar to that previously reported with the 18-ml pump in larger-sized children.