High-resolution shallow-seismic reflection (Uniboom) profiles obtained in inner and mid-shelf areas of eastern Mersin Bay (Turkey, northeastern Mediterranean) show that the sedimentary column comprises two major and distinct lithological sequences (C and B) separated by a reflector (R) which is interpreted as the pre-Holocene surface. The upper sedimentary sequence (C) is thought to represent roughly the Holocene and is characterized by parallel/divergent to sigmoidal reflection patterns above (Unit 1) and sigmoidal-oblique to disrupted, wavy and hummocky reflection configurations below (Unit 2). This may reflect changes in relative sea level and or depositional conditions during the earlier and later stages of Holocene. The Holocene sequence (C) reaches a maximum thickness of approximately 35 m about 500-600 m seaward of the mouth of Seyhan River and thins in all directions away from this point. Adjacent shelf areas are characterized by thinner (10-15 m thick) depositional sequences. Holocene sediment accumulation rates range from 1 to 3.5 m/ka.