Functional asymmetry of the brain as measured by indices of the leading arm (8 tests), leg, and eye has been studied on 217 healthy 2- 7 years old children and on 110 5-6 years old children with speech disturbances. It has been found out that functional asymmetry is already present by the age of 2. Disturbance of speech and speech-related functions results in disturbed development of righthandedness. When speech disturbances are relatively gross the motor asymmetry is less pronounced. It is assumed that lateralization of speech and motor functions in ontogenesis is a closely interrelated process.