Objectives:
The aim of the study was to answer the following questions: What are the main determinants of the sense of loneliness in parents of children with autism and what are they in parents of children with intellectual disability? Is sense of loneliness related to the intensity of specific personality traits in parents of children with neurodevelopmental disorders and to the perceived social support? Do parents of children with autism spectrum disorders differ from parents of children with intellectual disability in terms of perceived loneliness? Are there differences in the sense of loneliness between subjects of different sexes and between subjects bringing up children at different ages?

Methods:
The following research instruments were used: Polish versions of the De Jong Gierveld Loneliness Scale (DJGLS), the Ten Item Personality Inventory (TIPI-PL), and the Berlin Social Support Scales (BSSS) as well as the authors’ own survey questionnaire, consisting mainly of demographic questions. The participants were 116 parents of children with autism spectrum disorders and 81 parents of children with intellectual disability without symptoms of autism.

Results:
No differences were found in the level of the sense of loneliness between groups distinguished according to the type of disorder in the child, the child’s age, and the parent’s gender, but regression analysis revealed that its predictors connected with social support were different in the cases of parents of children with different neurodevelopmental disorders.

Conclusions:
The obtained results may be useful for therapists and social workers supporting parents of children with neurodevelopmental disorders.