Introduction: Autism is a pervasive developmental disorder characterised by abnormal development in the first two years of life and impairment with respect to the following three areas: social interactions, communication, and behaviour. The disorder is more common in males than females. The aim: The study was conducted to assess the effects of sensory integration therapy on selected fitness skills in autistic children. Material and methods: The study assessed a group of 20 children (15 boys and 5 girls) aged 3 to 10 years. All children were diagnosed with autism and underwent 2-year therapy. The children showed impaired sensory modulation with abnormal stimulus reception and processing in the tactile, auditory, vestibular (balance), olfactory, and gustatory sensory systems. The study assessed fitness skills and their correlations with sensory integration therapy used in the children. The assessment used the Sensorimotor Development Questionnaire developed by Zbigniew Przyrowski and selected tests from “Obserwacja Kliniczna” as well as history-taking conducted with the parents. The following aspects were analysed: muscle tone, static balance, dynamic balance, jumping on two legs, jumping on one leg, catching and throwing a ball, and self-care activities, such as putting on shoes. Results: Sensory integration therapy contributed to an improvement in motor, sensory, cognitive, emotional, communication, and social development in the study patients. Conclusion: The use of sensory integration effectively supports sensory processes in autistic children.