Autism is a neurodevelopmental disorder with symptoms arising that are apparent throughout the patient's lifespan. Autism Spectrum Disorders (ASD) are characterised by impaired social and communication interactions as well as restricted, repetitive interests and behaviour. Currently in Poland, about 50 000 people suffer from autism, of which 1/5 are children. Epidemiological studies show that the incidence of autism is increasing, which may be due to the diagnostic category of ASD having been developed. Of vital importance in the treatment of autism, is early diagnosis which is conducive to more rapidly improving the quality of patients' health. It is believed that both genetic and environmental factors may affect the development of the disease. Moreover, expert opinion emphasises the importance of making an adequate diagnosis when the first symptoms of autism start appearing which can be both psychological, gastro-intestinal and metabolic ones. Conventional treatment is based on the combination of behavioural and dietary therapy together with pharmacotherapy. For example, adapting an appropriate diet could help alleviate the disease severity, as well as the psychological and gastrointestinal symptoms. Much scientific research has indicated that pathogenesis of autism may have a beginning already in foetal life. During pregnancy, specialists should take special heed of metabolic disorders, which can increase the risk ofASD in children. One of the dietician's tasks are to properly assess the nutritional status of mothers before and during pregnancy, thereby allowing changes in nutrition to be made wherever necessary in order that metabolic indicators be improved. Thus an important part of autism therapy is the improving patient's nutritional status to prevent the onset of gastrointestinal symptoms. Adopting diets and tailored to individual disease symptoms, is linked to the nutritional requirements and food preferences of the patient. Specialists also emphasise that continual monitoring of the diet and nutritional status of children with ASD is required. It is also essential to start adequate dietary management in autistic patients with overweight, obesity or wasting, caused by improper nutrition. Frequently only a dietary therapy is insufficient to effectively treat autism. Many studies demonstrate the need to supplement the nutritional deficiencies of autistic patients with fatty acids omega-3, probiotics, vitamins and minerals in combination with medical and psychological interventions. A properly designed elimination diet adapted to the patient's individual may also lead to relief of the autism symptoms and the occurrence of gastrointestinal disorders. Parents and caregivers should therefore be aware of the benefits of nutritional therapy and need for proper monitoring the treatment of patients with ASD. A review of nutritional factors, dietary treatments and diet supplementation in patients with ASD is presented.