In this study, heavy metal levels in selected fly ash samples of various biomass types ( municipal solid waste, hazelnut shell, wheat straw, olive husk, walnut shell, almond shell, sunflower shell, and beech wood) were determined. The concentrations of Zn, Pb, Cd, Mn, Cr, Ni, Co, Cu, Sn, Sb, Se, V, Mo, and As metals were determined in the fly ash samples. Chemical analyses of biomass fly ashes showed that they were mainly composed of SiO2, CaO, K2O, and Al2O3. The highest heavy metal levels were found in MSW fly ash. The fly ash from beech wood has generally higher As, Cd, Pb, and Hg contents than those of agricultural residues. Compared with bottom ash, Pb and Cd concentrations in fly ash were 10 - 20 times higher. The fly ash samples from beech wood and hazelnut shell have aerosol particles of more than 30 and 10%, respectively.