In 2002, an extensive study was performed in forest sites of Izmir. This first study results led on the one hand, to quantify of Cs-137 and K-40 concentration in mushrooms collected in the Izmir region and to a first evaluation of dose in people due to the ingestion of radionuclide-contaminated mushrooms. The mushroom concentration values varied over a wide range from below detection limit to 401 +/- A 4 Bq kg(-1) (dry wt) for Cs-137. The K-40 concentration values obtained for different species of mushrooms ranged from 588 +/- A 26 Bq kg(-1) to 2024 +/- A 63 Bq kg(-1) (dry wt). The annual effective dose values due to mushroom ingestion for Cs-137 are lower than the ICRP-2007's reference level value of 1 mSv for "existing" exposure situation. Inductively coupled plasma-mass spectrometry was used to measure many alkali-alkaline earth elements and heavy metals in mushroom samples. The relationships among the concentrations of Cs-137 and the stable elements were presented and the occurrence of metals in mushrooms was evaluated.