The hydrology of Bayelva, which is located to the northwestern part of Spitsbergen, was investigated during the period 1974-78. The river drains a catchment of 31.5 km2, out of which 54% are covered by glaciers. Additional studies were carried out on erosion and transport of suspended solids in the river. The major part of the runoff occurs during the months June to August. The snow melting usually starts in late May or early June, when air temperature rises above o°C. Mean annual runoff during the period was measured to 31.8 × 106m3, which during an average runoff period of 109 days/year gives 3.4 m3/sec. Highest daily flood was measured to 32.2 m3/sec. Annual sediment transport (suspended load) varies from 6,646 to 16,558 t, while highest observed concentration was 3,830 mg/l. The high variations may be explained by annual runoff volume, frequency of floods, amount of rainfall and rainfall intensity.