The present study sough to apportion the possible sources of TSP in Ahvaz, southwestern Iran. A high correlation coefficient existed between measured and predicted values (R(2) = 0.99), indicating that the data were well modeled. Seven factors were resolved by the model: crustal dust (56%), road dust (7%), motor vehicles (8%), marine aerosol (9%), secondary aerosol (7%), metallurgical plants (4.5%), and finally petrochemical plants & fossil fuel combustion (8.5%). In contrast with crustal dust having higher relative contributions during spring and summer, motor vehicles had higher contributions during fall and winter. In addition, the latter had higher contributions during weekdays than weekends.