In work results of research of the MW irradiators for intracavitary treatment, executed in the form of longitudinal slots on a lateral surface of electroconducting cylindrical case and connected inphase or in antiphase are presented. The theoretical analysis is carried out with use of program HFSS 9.2 for four and six slot irradiators. It is shown, that distribution of intensity of MW field along slot on surface of biological tissue (BT) appears practically even for both types of connecting. Depth of penetration of MW field in BT depends on type of connecting of slots. Across irradiator greater evenness of a field on depth BT from 0 up to 2 mm is provided with irradiator with antiphase connecting of slots. Experimental researches are carried out for four slot irradiators. It is shown, that results of experiments are in agreenment with calculated data.