The alloys in the AgSbTe2GeTe system and the AgSbTe2PbTe system are known as excellent thermoelectric (TE) materials, i.e. TAGS and LAST, respectively. Although the TE properties of the AgSbTe2(Pb,Ge)Te system have not been reported. Here, we show the high-temperature TE properties of the alloys in the AgSbTe2(Pb,Ge)Te system. The samples of (Ag0.5Sb0.5Te)100−x(Pb0.16Ge0.84Te)x (x = 75, 80, 85, and 90) were prepared and the electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) were examined in the temperature range from room temperature to 720 K. The samples prepared by hot-press were composed of two phases: the GeTe-based matrix phase and the PbTe-based precipitate. These samples exhibited the moderate ρ and S as well as relatively low κ, leading to high thermoelectric figure of merit ZT (= S2T/ρκ, where T is the absolute temperature). The maximum ZT value was 0.84 at 720 K obtained in the sample of x = 80.