One of the common complaints of parents of infants is constipation. At the present time, based on the evidence, specialists (pediatricians, pediatric gastroenterologists, nutritional specialists) have developed modern guidelines for managing children with functional constipation. Data on the classification, diagnosis and treatment of this condition in infants are included in the standard of the new IV Rome criteria for functional gastrointestinal disorders in children (San Diego, May 22, 2016). The article discusses the assessment of the condition, diagnosis and therapy of functional constipation in children under 6 months. As a symptomatic correction of proctogenic and mixed constipation, experience is given and recommendations for the use of the rectal preparation Microlax®