This study investigated seasonal variations in mass concentrations of particulate matter (PM) and compositions of heavy metals in PM2.5 and PM10 collected from a typical urban residential area in Ulsan, Korea. PM measurements were conducted during spring and summer of 2009. Mean concentrations of PM2.5 in spring and summer were 23.2 and 18.1 µg/m3, respectively. Mean concentrations of PM10 in spring and summer were 45.9 and 33.2 µg/m3, respectively. The lower summer PM concentrations as compared to the spring ones are due to the increased rainfall precipitation. Airborne PM was analyzed for these heavy metals: Fe, Zn, Cd, Mn, Pb, Cu, Cr and Ni. All of the metals in PM2.5 and PM10 had higher concentrations in spring than in summer, except Cr in PM10 which shows similar concentrations between spring and summer. Seasonal differences in the metal concentrations may be due to differences in wind directions with some winds passing through industry or traffic areas. Analysis of enrichment factors of heavy metals showed highly enriched Cd, Zn, Pb and Cu. Principal component analysis for the heavy metals in PM2.5 and PM10 identified industrial emissions and road dust (soil and traffic) as major sources at the sampling site.