Studied the temporal and spatial variations of primary productivity in relation to chlorophyll a and phytoplankton during January to December 1993 in Gurupur estuary. The rate of primary production varied between 0.43 and 52.21 mg C/m³/hr. It exhibited a trimodal distribution showing primary peak during May, secondary peak during November and lower productivity during June - July. Chlorophyll a concentration varied between 1.69 and 10.59 mg/m³. The peaks of chlorophyll a coincided with peaks of primary production. Phytoplankton population varied between 1801 and 35009 cells/1showing major peaks during December, May and July. The periods of higher phytoplankton densities coincided with the peaks of primary productivity which in turn coincided with the lower concentration of nitrate and phosphate. Temperature and salinity showed positive relationship with primary production in Gurupur estuary.