The objective of the present study was to enhance the effectiveness of the treatment of the patients presenting with various forms of chronic tonsillitis (CT) by means of antimicrobial photodynamic therapy (APDT). The study included 48 patients at the age from 18 to 55 years divided into three groups; all of them suffered from various forms of CT. Group 1 was comprised of 12 patients given a course of traditional conservative therapy. Group 2 consisted of 17 patients treated by APDT while group 3 included 19 patients in whom a course of antimicrobial photodynamic therapy was preceded by the treatment of the mucous membrane of the palatine amygdalae with a lidase solution. The microbiological testing was performed on days 5, 12, and 24 after APDT and also within the next 6—9 months. The results of the microbiological and clinical studies give evidence of the possibility to improve the effectiveness of the treatment of chronic tonsillitis by means of antimicrobial photodynamic therapy with the use of the preventive treatment of palatine tonsillar mucosa with a lidase solution. Such treatment was found to facilitate degradation of theintercellular matrix of the biofilm and reduced its resistance to the photodynamic impact.