Abstract: Ash and mineral (Na2O, K2O, MgO, CaO, Al2O3, SiO2, TiO2, MnO, Fe2O3 and P2O5) content of 5 Phellinus mushrooms from the Northeast part of Thailand has been measured using X-Ray Fluorescence (XRF) spectrometry. A method for determination of trace levels of germanium by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) with chemical matrix modifier and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was compared. The preparation of sample solutions for determination of trace levels of germanium by wet method and dry ashing method was studied. It was found that none of the cations interfered GFAAS by using palladium strontium and nickel as new matrix modifier and the linear correlation range was 0.0040-1.00 mg L-1 and the detection limit was 0.0041 mg L-1. The GF-AAS was applied to determine of trace levels of germanium in part per million (ppm) level in some Phellinus mushrooms with a recovery range of 75-95% which the results agree with the ICP-MS (81-111%). The ICP-MS was applied to determine of germanium in part per billion (ppb) levels in some Phellinus mushrooms with containing 0.32-1.56 ppm. The wet method for preparation sample solutions was not successful while dry ashing method was successful.