The purpose of the study: to evaluate the clinical and functional efficacy and safety of the solution for nebulizer FLU-ACYL broncho in inhalation in patients with chronic bronchitis to prevent exacerbations in remission. Object and methods of research. The study included 60 patients aged 25–55 with chronic bronchitis in remission, who had a history of at least 1 exacerbation per year for the last 3 years. Patients were divided into groups: 1st (n=30) — used FLU-ACYL broncho (1 inhalation per day for 10 days), 2nd (n=30) — ambroxol (1 inhalation 22.5 mg per day). Examination of patients was performed before treatment, on the 11th day from the beginning of treatment and in the long term after the end of therapy — 30 and 80 days. Results. A positive result of the use of FLU-ACYL broncho is achieved in 100% of patients after a 10-day course of inhalation. A positive effect on the nature and structure of sputum in patients using FLU-ACYL broncho occurs during the first three days of treatment, which is significantly faster than in the group of ambroxol (mostly from 3–4 days of therapy) (p<0.01). In the group of FLU-ACYL broncho 100% of patients have a significant positive effect on the symptom of cough during the 10-day course of inhalation, while in 40% of them — during the first 5 days of therapy. In the group receiving ambroxol, a decrease in the severity of cough symptoms within 5 days was observed in only 23.0% of patients, in 43.0% — within 10 days of inhalation, and 34.0% had no significant improvement in cough after treatment (p<0.05). According to the Breathlessness, Cough and Sputum Scale (BCSS) and the Chronic Bronchitis Symptoms Assessment Scale (CBSAS), in patients after 10 days of FLU-ACYL broncho significantly longer observed post-therapeutic positive effect on respiratory symptoms compared with the group of ambroxol with significantly better indicators of forced expiratory volume for 1 second, peak expiratory volume rate, increase in maximum volume at level 25 (p<0.05). After a 10-day course of inhalation of FLU-ACYL broncho, the duration of remission is 70.4±5.99 days, which is significantly longer than in the group of ambroxol (55.5±7.62 days) (p<0.01). The use of both drugs avoided exacerbations of chronic bronchitis in patients of the observation group within 46–90 days from the start of therapy, i.e at least 6.5 weeks in 100% of patients with benefits in favor of FLU-ACYL broncho. Conclusions. FLU-ACYL broncho nebulizer solution is a medical device with high clinical efficacy in patients with chronic bronchitis. The obtained data suggest the feasibility of using a 10-day course of FLU-ACYL broncho 1 time in 3 months for year-round prevention of exacerbations of chronic bronchitis (1 time in 3 months, 4 times a year), which may confirm the results of longer studies with FLU-ACYL broncho throughout the year.