Data on carbon dioxide components, collected just before SW monsoon 1986, have been analysed. Total carbon dioxide (TCO sub(2)) and titration alkalinity are higher in the northern and western Arabian Sea compared to those in the southern and eastern regions, while the concentrations are the highest in the northern part. TCO sub(2) relations with apparent oxygen utilization and phosphate suggest northward decrease in carbon dioxide production per unit oxygen consumption. Despite the high biological production in the western Arabian Sea, relatively low CaCO sub(3) dissolution (approximately 100 mol dm/3 near and below 3000m) is attributed to skeletal material incorporation into faecal material and the subsequent faster deposition rates. Arabian Sea water is found to be undersaturated around 200-400 m and 200-600 m with respect to aragonite and calcite, respectively