The aim of the study was to evaluate the influence of fertilization with sewage sludge and biosolids on heavy metal content in white mustard (Sinapis alba) seeds. The study was conducted in 2012 on experimental plots in the State Higher Vocational School in Suwałki. Each research area was divided into 3 blocks 18 m2 each, constituting repetitions. The test areas were fertilized with three different fertilization variants with sewage sludge biosolids: K1-sewage sludge, K2-sludge subjected to a process of composting with a three-month compost organic waste and K3-sludge subjected to the composting process with a three-month compost organic waste from the biological preparation Trigger-4. The samples of sewage sludge were collected for the analysis and one determined its basic physical, chemical, microbiological and parasitological properties, in accordance with the requirements of the Decree of the Minister of the Environment of July 13th 2010 on municipal sewage sludge (Journal of Laws of 2010 No 137 item. 924). Based on these results, it was found that the cadmium concentrations in the seeds mustard ranged from 0.2 mg/kg s.m. on plots with the variant K3 to 0.93 mg/kg s.m. in the variant K1. On the other hand, lead content ranged from 0.3 to 4.25 mg/kg s.m. which shows that none of the analyzed samples met the standards for lead and cadmium contained in the Decree of the Minister of Health of January 13th 2003. The statistical analysis indicated that the concentrations of Cd in mustard seed was significantly correlated with the concentrations of Ni and Zn (respectively, r=-0.89 and r=-0.54). There were significant positive correlations between soil pH and metal concentrations in the seeds of mustard. The pH was significantly correlated with Ni (r = 0.60) and Zn (r = 0.55) at a p≤ 0.05.