ABSTRACT.Sensory‐motor and cognitive functioning was investigated in a group of 32 children treated with bone marrow transplantation (BMT), 1–6 years after treatment. Twenty‐five of the patients had suffered from leukemia. The BMT procedure had involved a regimen of cytostatic drugs and, for leukemia patients, total body irradiation at a dose of 10 Gy, administered in one session. Cytostatic drugs and irradiation are known to be potentially neurotoxic, particularly when combined. The examination involved four neuropsychological tests of sensory‐motor and cognitive functioning, as well as an age‐appropriate intelligence test. For control the bone marrow donors (n=32), siblings of the patients, were also investigated. A pronounced delay in motor development was found in four children, who had been treated with BMT including total body irradiation before 3 years of age. Patients between 3 and 11 years of age at BMT were at a slight disadvantage, compared to donors, on tasks involving perceptual and fine motor speed. In older patients no deficits were