An aerosol monitoring study was conducted to measure the fine particulate matter (PM2.5 and PM1) concentrations and composition in the urban area of Istanbul, the most populated city in the north-west of Turkey. The sampling station was located near the D-100 highway. The PARTISOL particulate matter sampler was used during the campaign and operated from 24 April 2009 to 24 May 2009 for PM2.5 and from 11 December 2009 to 9 April 2010 for PM1. Nineteen PM2.5 samples and 17 PM1 samples were collected. The glass fiber filters were weighed before and after sampling to obtain mass concentrations. Then X-ray fluorescence was used to measure the concentration of 23 elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, As, Rb, Sr, Y, Mo, Ba). PM2.5 concentration ranged between 23.8 mu g/m(3) and 81.5 mu g/m(3) and PM1 concentrations were between 7.6 mu g/m(3) and 30.2 mu g/m(3). As a result of the principal components analysis (PCA), PM2.5 metal emissions were dominated by significant anthropogenic sources, as expressed by high factor loadings in S, Cr, Zn, Cu and K. Crustal elements were likely related to first component (high loadings in Mg, Al, Ba and Si) for PM2.5 and third component for PM1.