In the present study, besides the clinical activity and safety of rokitamycin in patients with episodes of breakthrough chronic bronchitis, its influence on the production of secretory immunoglobulins of group A (sIgA) at the bronchial level was studied. Fifteen patients (12M, 3F), of mean age 51.0 years 7.0 SD were treated with rokitamycin in 400 mg tablets (2 tabs/day) for 10 days. The results attained confirmed the therapeutic efficacy of rokitamycin, with a clear improvement of symptoms already by the 5th day. The levels of sIgA in bronchial secretions showed on the 10th day a statistically significant increase, superior to that reported in the literature for other antibiotics, passing from 18.2 microg/mL 0.9 SEM at the baseline to a value of 19.4 microg/mL 0.9 SEM. The high therapeutic safety of rokitamycin should be emphasised: it determined no variations in the laboratory parameters considered; in the course of treatment no patients suffered adverse events. The results attained, which confirm the clinical efficacy of rokitamycin and complete its pharmacodynamic profile, allow us to advise the use of this macrolid with 16 carbon atoms in acute infective pathologies of the respiratory tract.