Monthly population fluctuations of plant parasitic nematode population associated with root of cotton in central province fields in Syria were studied over a 2-year period 2008-2009. In both years, the differences between monthly samples were not significant. Average of nematode population density in soil decreased after sowing (May) and near the end of the season (at harvest) in both years and in all of the central province fields, then the numbers of nematode increased slowly again in June to reach a peak at mid-season (July). Ghab region had the higher population density (1180.8 juveniles/100cm3 soil). An increase in numbers of nematode in soil was accompanied with a decrease in number in roots. Negative correlation was observed between average of the initial population density and reproduction factor. Pratylenchus, Meloidogyne incognita, Rotylenchulus, Tylenchorhynchus were dominant nematode species in these fields. Also, the infestation of the first three nematode species was not uniform.