In glacier-dominated catchments, glaciers have an important effect on the water balance. It is important to understand the glacier control on inflow in order to assess historic trends and future scenarios. The mass balance of a 100 km2 glacier sub-basin of Svartisen ice cap, northern Norway, was reconstructed for 1917 to 1995. The reconstruction was carried out using three different methods, the hydrological method, the correlation between mass balance and meteorological observations and a precipitation-degree-day model. Calibration data were derived from field observations, map comparisons and correlation of observations at different glaciers. The reconstructed series showed a total loss of ∼3 × 109 m3 of water, most of which occurred between 1920 and 1950. After 1950, the net balance increased gradually and is currently near equilibrium with the present climate. Suggested climate scenarios for this region gave a loss between zero and 5 ×109 m3 of water until the year 2050.