Investigations were carried out to understand the distribution of phosphorus and its relationship with some chemical constituents and biological aspects in the clay-sized bottom sediments of the eastern part of Bay of Bengal collected during a cruise on "Anton Brunn" in 1963. Concentration of phosphorus varies regionally in these sediments with a significant increase from north to south. The increase in the phosphorus content with decreasing iron content in the clayey sediments does not support the probable fixation of phosphorus as ferric phosphate. The sympathetic relationship of phosphorus with calcium and the presence of calcareous material strongly suggest the possible fixation of the phosphorus as calcium phosphate. Both phosphorus and organic matter contents are low in the northern part, where there is abundance of river-borne terrigenous material. This indicates that phosphorus is not brought from the continental source in notable amounts. It is inferred that the increase in phosphorus content in the southern part is due to high planktonic production and lack of continentally derived terrigenous matter and that the phosphorus here is mostly biogenic in origin.