Hydrographic and chemical conditions in the Gulf of Cariaco are influenced mainly by variations in upwelling, which are intimately associated with the wind regime. Displacement of water in the gulf is primarily controlled by prevailing winds from the E-NE direction, which enhance the outflow of surface waters and the inflow of the denser upwelled waters. Although seasonal variations of salinity in the gulf are relatively small, water temperatures fluctuate considerably with the change in the inflow rate of the upwelled subsurface waters. Using weekly water temperature and phosphate concentration data collected during 1974 and 1975, the rate of water renewal and phosphate input into the gulf were determined by setting up a simple model. Is was found that the flush rate varies seasonally with the wind regime. Flushing was completed in approximately 21 days in February 1974, which was the shortest lapse (period of strong winds) and 111 days from June through October 1975, which was the longest lapse (period of weak winds). The influx of external water was estimated to be 245 x 10 m³ in 1974 and 188 x 10 m³ in 1975. Such influx corresponds roughly to 8 and 6 times as much as the whole volume of the gulf. The annual input of phosphate phosphorus was estimated to be about 3,350 tons in 1974 and 2,510 tons in 1975.