Background and Purpose Little is known about the gross motor development of children with Hurler syndrome who have undergone umbilical cord blood transplantation (UCBT). The purpose of this study was to provide a description of gross motor development in children with Hurler syndrome after UCBT. Subjects and Method Longitudinal changes in gross motor abilities were documented on the gross motor subtests of the Peabody Developmental Motor Scales, second edition (PDMS-2) for 21 children with Hurler syndrome. Each child was assessed between 1 and 6 times after UCBT. The participants had a mean age ([+ or -] SD) of 32.2 [+ or -] 16.0 months at the time of the first assessment. The mean time ([+ or -] SD) between UCBT and the first assessment was 16.2 [+ or -] 16.5 months. Results The participants had marked gross motor delays, with a mean gross motor quotient 2 standard deviations below the mean for children who were developing typically. The rate of development differed between the subtests of the PDMS-2. The participants gained abilities at the slowest rate on the stationary subtest and at the fastest rate on the locomotor subtest. Discussion and Conclusion The participants had varying degrees of delay in different gross motor domains. While gaining new gross motor abilities over time, these children continued to have delays up to 48 months after UCBT. Physical therapists treating children with Hurler syndrome after UCBT should use assessment tools that will capture these differences and should individualize treatment plans accordingly. Additional research is needed to document the efficacy of physical therapy intervention with this population.