Particle-bound polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were monitored at two sites in northern Greece for an eight-month period in 1999. PCDD/F concentrations were close to the lower end of reported values worldwide. Excepting a few cases, the PCDD/Fs homologue profile was stable. The gaseous PCDD/F fractions calculated were found to account for a small percentage of the total concentrations (<2% for OCDD/Fs and HpCDD/Fs, while 30-35% for TCDFs). Particle-bound PCBs were also found at low concentrations which, however, were higher at the urban site. Calculations of the dry deposition of particulate PCDD/ Fs and PCBs gave mean values of 0.52 and 0.59 pg I-TEQ/m2/day of PCDD/Fs, while 242 and 74 pg/m2/day of sigmaPCBs for the urban and the semirural areas respectively. An anticorrelation of PCDD/F concentrations with ambient temperature was derived particularly for the lower chlorinated congeners. A weak association with winds of western and southern origin was also observed. Factor analysis and literature source profiles were employed to identify possible emission sources. It was appeared that the PCDD/F compositional pattern of TSP is influenced by mixed sources the most prominent being uncontrolled fires and car exhausts.