The influence of early manipulatory skill training on forepaw preference in adult state of rats was investigated. One group of Wistar rats was trained at the age of 21–28 days of life, another one at the age of 30–37 days of life. Second test of both groups was performed at the age of 120–127 days of life. It was found that after training at the age of 21 days of life adult rats had less expressed predominance in forepaw use and showed ambidextrous tendencies while most rats trained at the age of 30 days of life were lateralised. It is possible to suppose the existence of sensitive formation periods for forepaw preference based on whole organism growth.