The present study maps the possible sources of unreliability of child's testimony (lower ability to remember and recall events, high suggestibility, easier formation of false memories, misunderstanding of the processes and interactions in surroundings, probability of deliberate lying) as well as its potential benefits in research and counselling practices. There are some procedures that can help improve or conversely depreciate information given by child. Child's ability to understand their own motivation, experience and behaviour as well as behaviour and feelings of others are often questioned. But despite all mentioned risks, child's testimony is very useful not only in judicial proceedings in which the child may be the only witness to the events but also in psychological research and counselling. It turns out that a child is more sensitive to some aspects of family life (conflicts) than an adult and gives even more accurate information than its parents. Child's view of family life is important for understanding its behaviour and experience.