Daily variations of salinity at nine selected stations in the Chilka lagoon spread over the entire area during the monsoon season from June to first week of October 1996 and seasonal variations in four sectors including outer channel of the lagoon during 1996 and 1997 were studied. Daily observations on the surface and bottom salinity values showed sharp declining trend from July to October in northern sector and outer channel with wider range of variations, while in the southern sector, the values increased slowly during June-August and decreased during September-October with minimum range of variation. Maximum range of variations in the monsoon salinity values were observed at station-6 followed by station-7 and the minimum range was recorded at station3 which is a deeper basin. Seasonal variations during 1996 and 1997 showed single oscillation in four sectors and for the whole lagoon. The pattern of seasonal changes in the salinity values showed gradual rise from November to March and sharp rise there after till June. Low salinity phase in the nothern and central sectors continues for about 8 to 9 months (July-February/March) and high saline phase in the outer channel continues for 7 months (December-June). Interestingly, the highest and the lowest salinity values were recorded at station-6 in the nortthern sector. Monsoonal intensity, weak ingress of semi-diurnal tide, slow discharge of flood water through shallow Muggermukh area and long outer channel (35 km), shallow northern sector, deeper southern basin and week circulation cause spatio-temporal variations in the salinity regime.