The distribution of primary production (mgC/m³) and chlorophyll-a (mg/m³) in surface waters at the regions between Cabo Frio (Lat. 22º 31'S - Long. 41º 52'W) and Santa Marta Grande Cape (Lat. 28º 43'S - Long 47º 52'W) is presented. The results were obtained during four oceanographic cruises: May/76, Sept-Oct/76, Jan-Feb/77 and Jan/78 by R/V "Prof. W. Besnard". The highest values for chlorophyll-a and primary production were observed during summer. In general, in all the experiments, coastal waters showed a greater primary production potential. The reasons for the eutrophication of coastal waters are discussed.