Fibroblast growth factor receptor‐3 (FGFR‐3) regulates aspects of bone development. Mutations in the FGFR‐3 gene (Fgfr3) in humans and mice produce vertebral abnormalities and bone deformities. The present study evaluated the behavioural concomitants of theFgfr3−/− mutation.Fgfr3−/− null mutant mice displayed severe impairments of motor abilities as detected on the rotarod, wire hang and open field tests. Absence of prepulse inhibition of acoustic startle was seen at prepulse levels from 74 to 86 dB. The motor deficits appear to be a direct and predicted consequence of the skeletal kyphosis, scoliosis and long bone overgrowth previously reported inFgfr3null mutant mice. The behavioural phenotype displayed by these mutant mice complements their anatomical, physiological and biochemical phenotypes, to complete the characterization of the functional outcome of a single gene mutation. Simple, robust behavioural symptoms, such as poor rotorod performance inFgfr3knockout mice, can provide useful surrogate markers to evaluate pharmacological treatments and gene therapies for human genetic diseases.