Over the last 20 years, a wide spectrum of congenital anomalies have been described in association with Kabuki syndrome (KS). However, very little information is available on developmental outcome. As more individuals with this syndrome are recognized and reported, it appears that as many as one-sixth may have normal intelligence. The purpose of this report is to describe the developmental outcome in 15 patients with KS, to determine whether a recognizable pattern of disabilities exist, and whether developmental outcome correlates with the presence of malformations. We ascertained 15 patients with KS from three dysmorphology and clinical genetics services in which developmental milestones and formal developmental testing were available. Based on these patients and a review of the literature, in the absence of major structural brain anomalies, the average intelligence quotient (IQ) in patients with this condition fall within the mild mental retardation range, however, specific developmental outcomes are widely variable, ranging from severe MR to normal intelligence. The presence or absence of hearing loss or major malformations, other than those involving the brain, was not predictive of developmental outcome.