Phytoplankton composition, abundance, and distribution were studied in summer 1996 along a transect in Kongsfjorden, a High Arctic fjord located along the north-west coast of Spitsbergen (79 o N) and influenced by temperate oceanic waters from the North-east Atlantic as well as freshwater and sediment discharges from adjacent glaciers. Kongsbreen, a retreating tidewater glacier at the south-east head of the fjord, has a major impact. At outer and intermediate fjord locations, phytoplankton composition was dominated by the chrysophycean Dinobryon balticum, reaching abundances of 2-4x10 6 cells dm - 3 . Associated phytoplankton, with a share of 15-20%, consisted mainly of dinophyceans, cryptophyceans, and unidentified (predominantly autotrophic) flagellates. Diatoms occurred in appreciable amounts only at the outermost parts of the fjord (2x10 5 cells dm - 3 ). Close to the front of Kongsbreen, the abundance of all higher taxa encountered was strongly reduced, while chrysophyceans were missing. More distant from the glacier (mainly in the inner fjord basin) the numbers of flagellated groups were comparable to those of the outer fjord area, with the exception of D. balticum. Diversity and evenness indices increased probably as a consequence of a balancing effect due to glacial discharge affecting species numbers and abundance. Examination of abundances and physical variables by correlation analyses and multivariate techniques (clustering/MDS) suggests that glacier-induced turbidity and subaquatic light availability modified the phytoplankton community structure to various degrees.