Along arctic coasts consisting of unconsolidated sediments in permafrost, and especially where these sediments are ice‐rich, the thermal energy of the sea water is added to the normal erosive impact of the waves. The resulting process of erosion due to the combined action of the mechanical and thermal energy of the sea is termed thermal abrasion. This study concentrates on almost every aspect of the retreat of coastal cliffs and changes in the sea bed resulting from this process. The author's fieldwork on Muostakh Island near Tiksi forms the core of the study. Attention is focused particularly on the shape and height of the resulting cliffs, coastal retreat rates and subsequent lowering of the sea bed. In addition attempts are made at calculating rates of thermal abrasion based on water temperature and period of wave action, and of thermal denudation of the subaerial cliff based on air temperatures, solar radiation and the ice content of the sediments. The rate of thermal abrasion of ice‐rich coasts is three to four times greater than the rate of normal coastal abrasion in comparable non‐frozen sediments. The reliably established record rate of current thermal abrasion is 55 m/year. The maximum sustained average rate, based on many years of observation, is about 10 m/year, while the prevailing average rate along the Soviet arctic coast and the major arctic islands ranges between 2 and 6 m/year. Attempts are made at estimating variations in these rates throughout the Holocene and at determining the amount of land which has been eliminated as a result.