The aim of the study was to assess the effect of lysozyme with varying activity on the microbiological stability and sensory attributes of chicken breast muscles. Lysozyme solutions with the activities of 2 400, 6 000 and 12 000 U/ml, applied in the experiment, were sprayed onto the surface of the muscles. Microbiological analysis was conducted on the day of production, as well as after 48, 72, 120 and 144 hours of storage at the temperature of 4°C. Total count of aerobic bacteria was determined along with the determination of indicator and pathogenic bacteria. Sensory analysis was performed evaluating the appearance, colour, texture and aroma of the meat. It results from the conducted examinations concerning chicken breast muscles that lysozyme exhibited inhibitory action towards aerobic and indicator bacteria. The application of a lysozyme solution with the activity of 12 000 U/ml proved especially effective, as it reduced the number of aerobic bacteria twenty times. The obtained results indicated that lysozyme may be an effective agent prolonging the wholesomeness of portioned poultry meat.