Abstract: Average labile forms of iron from the bottom sedimans of the Marmara Sea is 50% of the total iron and dominant ion is Fe².Fe² is the dominant species of the labile forms at the shallow areas; whereas Fe³ is dominant at the deeper part of the basin. Thelabile form distribution of iron indicate that oxidation state of the Marmara Sea sediments is reverse of that of the Black Sea: i.eanoxic sediments are round at the shallow levels and generally oxic sediments are recovered at the depth of 480 m. The dominance of Fe² near coastal areas is related to high sedimentation rates and reduction processes in the bottom sediments. These reduction processes could be related to decomposition of organic matter which is generated either by primary biological productivity of thesea by terrestrial input. The increase in the amount of Fef3towards the deeper part could be explained by low sedimentation ratesand long term bottom current activity of Aegean Sea in the study area. Bottom sediments of the Marmara Sea could be oxidised bythis long term ventilation processes and associated sea water-sediment interactions under the low sedimentation conditions.The oxidic level of the deeper part of the Marmara Sea (110-480 m.) which is mainly composed of Fe³constitutes favorable conditions which allows the trapping of the heavy metals within sediments; where as reducing conditions at the shallow water areasgive rise to the dissolution of heavy metals from the sediments and then migration in the sea water.Weak positive correlation between labile forms of iron and organic matter implies technogenic iron input. The increasing values of Pb, Zn, Ni, Cu on the upper levels of sediments is related to both diagenetic migration and technogenic-antropogenic contamination. Fe21 Fe³ values of the northern coast are higher than those of the southern coast. This difference may be due to effect of the bottom water current pattern of Aegean Sea in the study area, which causes oxidasition of deep sediments particularly in the south.