This paper presents an assessment on the dispersion of the Itajaí-Açu estuary plume under different river discharge conditions. Three oceanographic cruises were carried out at January, February and March 2000 on the adjacent shelf off Itajaí, when salinity, temperature and particulate suspended matter data were acquired in vertical profiles using a ctd probe. The river discharges during the cruises were 556, 227 and 214 m3.s-1, respectively. The results pointed out that the river discharge is the main factor driving the plume dispersion. The concentration of the particulate suspended matter and the proportion of fresh water is directly related to the discharge. It was observed also that the plume dispersions is predominantly towards Northeast.