Experimentally determined AC loss i n Bi2223tapes at 4.2K under applied D C magnetic field is discussed.Considered are the influences on the seif-field loss of:(1)The applied DC field(2).The resistivity of the sheath materia l.(3)The critical current and the number of superconducting filaments.All o f the experiments are performed at 4.2K and at appled magnetic fields of up to 5T.