The study included 93 patients (mean age 56.8+/-7.2) with COPD; 22 presented with grade 1 COPD, 36 and 35 with grade II and 111 COPD respectively. The latter group displayed reduced absorption of fats, proteins, and carbohydrates in the small intestine, the degree of dysfunction increasing with the severity of the disease, degenerative/dystrophic changes in intestinal mucosa, and deterioration of its regenerative potential. The data obtained are interpreted in the context of the relationship between the functional/structural properties of intestinal mucosa and clinical manifestations. The body mass deficit in COPD patients was shown to positively correlate with the reduction of absorption of fats (r=0.55), proteins (r=0. 71), and carbohydrates (r=0.48) in the small intestine.