Diurnal (24-h) samples of fine particulate matter (PM2.5, ambient particles with an aerodynamic diameter not greater than 2.5 μm) and soil samples were collected in an urban area in Warsaw, in winter. The samples were analysed for 24 elements with an Epsilon 5 spectrometer (PANalytical). The results were then arranged and compared with the results of research conducted earlier in Poland and other parts of the world. Afterwards, sources of ambient PM2.5 were identified and the share of each in the concentration of PM2.5 was eval- uated by means of enrichment factor (EF) analysis, principal component analysis (PCA) and multi-linear regression analy- sis (MLRA). The results were interpreted using a detailed analysis of correlations between diurnal concentrations of PM2.5,PM2.5-elements,andofchangesinmeteorologicalcon- ditions. The winter average ambient concentration of PM2.5 in Warsaw, was 10.7±7.5 μg/m 3 and was muchlower than in the other sites in Poland. In Warsaw, regardless of the concentra- tion of PM2.5, the concentrations of certain PM2.5-bound ele- ments, mainly toxic, were high, e.g. the average ambient con- centrations of PM2.5-bound Se, As, Co, V, Cd and Ni were 12.7±30.5, 10.6±34.4, 9.4±13.7, 15.1±32.7, 9.6±22.2 and 3.5±5.0 ng/m 3 , respectively. The elemental composition and concentrations of PM2.5 appeared to be influenced mainly by