The article presents the results of an empirical psychological study of the relationship between brothers and sisters from full and incomplete families. The aim of the study was to identify the psychological features of sibling relationships in families of different types, using 2 methods: "Diagnosis of sibling communication" and "Sibling questionnaire". The sample size was 100 people: 50 siblings from each type of family. According to the method of "Diagnostics of sibling communication", trust, unity of views and disagreements related to elections, circle of interests, attitude to life in a group of siblings from full-fledged families was revealed higher than in incomplete ones. According to the method of the "Sibling questionnaire", our study showed that siblings from full-fledged families have common interests, life experience and experiences, as well as a desire for power over another sibling is higher than that of representatives of incomplete families.