Clarythromycin (Clerimed) is an antibiotic that has a high antibacterial potential, is successfully used in the treatment of moderate and severe exacerbations of Stage II chronic obstructive lung disease (COLD). Comparison of the clinical efficacy of Clerimed with beta-lactams and respiratory fluoroquinolones has indicated the equal clinical efficacy of the compared groups of drugs. A functional and laboratory monitoring of patients with an exacerbation of COLD treated with Clerimed has established that the most pronounced changes (improvement) occur within the first week of antibiotic therapy, which is typical of control patients. The side effects of Clerimed have been found to occur not more frequently than those of other antibiotics and they are considered to be slight. Clarythromycin may be recommended for the starting therapy of exacerbations of COLD in everyday practice.