Seasonal (winter monsoon, intermonsoon and southwest monsoon) and interannual (between southwest monsoon seasons of 1995 and 1996) variations in total carbon dioxide (TCO sub(2)) and partial pressure of CO sub(2) (pCO sub(2)) were studied in the central and eastern Arabian Sea as a part of the JGOFS (India) Programme. The PCO sub(2) values were computed from the results of coulometric TCO sub(2) and spectrophotometric pH measurements. Seasonal variability in TCO sub(2) is evident with the changing circulation and biological production. In all seasons, the pCO sub(2) is higher in surface waters of the Arabian Sea, except along the Indian coast in the southwest monsoon, than that in atmosphere, and thus this region appears to be a perennial source of atmospheric CO sub(2). Significantly, an average of approx 45 Tgy sup(-1) could be ejected to atmosphere from the study region, that seems to far exceed the earlier estimations. The estimated fluxes, however, are in agreement with those from the eastern equatorial Pacific Ocean