A study on the species variety of the Mallophaga on domestic chickens in the region of Stara Zagora was performed. In the period of 1994–2003, a total of 647 birds from both genders from breeds prevalent in the region were studied, in 64 small private farms utilizing extensive rearing technologies. Biting lice infestation was found out in 589 birds. A total of 21 462 individuals of the Mallophaga group were collected and identified. They were determined to belong to 4 species of the Phthiraptera order: Menopon gallinae (Linné, 1758), Eomenacanthus stramineus (Mönnig, 1934), Menacanthus cornutus (Schömmer, 1913), and Goniocotes gallinae (De Geer, 1778). Dominating among them was M. gallinae (35.9 % of all identified Mallophaga), followed by G. gallinae (25.8 %), and E. stramineus (23.3 %), while M. cornutus had the lowest share of occurrence (15.0 %). The population structure of each proven species of biting lice was established. The species variety of Mallophaga on chickens was relatively poor, constant, and not varying in time, which can be explained with the absence of considerable climatic differences within the boundaries of the tested region.