An investigation was carried out on 244 rats (71,9% sewer rat; 27,7% black rats, 0,4% house mouse) with various index 30-40, which was increased and kept at high level from March to September. 268 fleas were collected (only 1 species of X.cheopis), the flea index oscillated from 0,11 to 1,90 and reached the highest level in April all isolations determined Y.pestis negatively. Flea resisted to malathion 5%, pyrethroid group was the greatest effectiveness