In the samples of fresh dehydrated sewage sludges from municipal treatment plants in Grajewo, Bielsk Podlaski, Sokółka, Dąbrowa Białostocka, Knyszyn, Mońki, Augustów, Suwałki, Sejny and Suchowola the following determinations were made: pH, pseudo-total content of Pb, Cd and Cr, organic matter and dry mass. The contents of the above-mentioned elements in fractions were evaluated using modified BCR method (four fractions: 1-acid soluble and exchangeable, 2-reducible, 3-oxidizable, 4-residual). The lead content (mean values) in particular fractions can be arranged quantitatively in a sequence: F4 (51.4%) > F2 (30.3%) > F3 (19.2%) > F1 (7.2%), in the case of cadmium: F4 (49.0%) > F2 (23.6%) > F3 (18,9%) > F1 (15.5%) and in the case of chromium: F4 (65.0%) > F3 (30.6%) > F2 (6.8%) > F1 (3.1%). Cumulative content of lead in mobile fractions (F1+F2+F3) ranged from 20.7% to 89.9%; for cadmium from 32.9% to 76.9% and for chromium from 27.5 to 58.6% of pseudo-total content.