oxidable poc, at two stations in the cananéia estuary, was found to be largely dependent upon the smallest size poc. the correlation factors between poc and the numerical abundance of cells, heterotrofic particles and bacteria, in each of the size categories studied, were generally low and non-significant for both stations, with a few exceptions. at st. i the number of heterotrophic particles seems to account for some of the poc variation over the year. at st. ii, the only significant correlation found was between the number of the largest and intermediate size classes bacteria and the equivalent size classes poc. at this station the importance of the detritus component is suggested. the differences found between the stations, concerning the numerical contribution of cells, particles and bacteria to total poc, have been attributed to the differential hydrodynamic conditions acting upon material coming from land, due to diverse location of the stations. sampling date and the collection of different water masses have also been considered as factors that may greatly affect the relationships studied.