After PDT, the levels of Ki-67 expression decreased statistically significantly (p < 0.05) relative to the initial values, amounting to 30.0 (27; 33.0)% in women with severe intraepithelial squamous cell lesions; in the group of patients with CIS, the value of the indicator was 29.0 (26; 31.0)%. The gene discussed is MKI67; the disease is in situ carcinoma.