Objective. To comparatively analyze pleural and peritoneal adhesions and to evaluate the clinical significance of their formation. For more than 100 years, surgeons have been finding the answer to the question of what the adhesive process is: a compensatory-adaptive response, genetically determined predisposition to adhesioenesis, or an individual nosological unit. The International Classification of Diseases, Tenth Revision, presents intraperitoneal adhesions (K66.0). Acute intestinal adhesions with obstruction (K56.5) are encountered in 13.9%; chronic pelvic pain (N73.6) occurs in 25—30% of cases following obstetric and gynecological surgeries. As surgery develops, repeated surgery, including that for adhesive disease, is coming into more increasing use. Ways to prevent and reduce adhesioenesis are sought in several directions simultaneously; the current ways of preventing adhesions have been now clearly formulated, which are aimed to reduce the traumatic effects on the peritoneum, to prevent inflammations at the surgical site, to decrease fibrin deposition into the abdominal cavity, and to create protective mesothelial barriers. The detection of abdominal adhesions unequivocally requires that a general surgeon should control the latter; however, the attitude of thoracic surgeons towards pleural adhesions is different. Some authors consider that adhesions prevent lung excursion and that pneumolysis increases the efficiency of treatment for destructive pulmonary tuberculosis. The attitude towards pleural adhesion formation cannot be regarded as that to a negative phenomenon, since stimulated adhesiogenesis may be a necessary component of treatment in some cases (chest trauma, residual pleural cavity, spontaneous pneumothorax, etc.).