Author presents the first (theoretical) part of the paper focused on comorbidity of substance use disorders in eating disorders. There are defined terms and shown epidemiological data together with hypotheses explaining this phenomenon. There is substantial literature evidence that supports higher than expected rates of co-occurrence of these two groups of disorders. Comorbidity of substance use and eating disorders has an influence on diagnostic difficulties, more complicated therapy and uncertain prognosis. The literature data help us to understand the cues behind and to realize integrated approach in the diagnostic and therapeutic process.

Key words: eating disorders – psychoactive substances – comorbidity