Measurements from ice cores and snow pits collected over the last 50 years are used to examine how net surface mass balance varies across the Antarctic Peninsula to give the first detailed map of mass balance for the region. A total of 211 reliable mass balance measurements were available for the preparation of the map, but some areas were found to be very data sparse. The analysis suggests that the largest values of mass balance are found along the spine of the northern part of the peninsula, where over 2.5 m yr-1 water equivalent (WE) has been measured. A secondary peak of more than 2.0 m yr-1 WE is determined along the mountains of eastern Alexander Island. Precipitation minus evaporation (P-E) fields from the European Centre for Medium-Range Weather Forecasts reanalysis project are compared with our analysis of in situ data. The model fields are found to have peak values of P-E of only half the amounts found from the measurements; the greatest model values are located on the western side of the peninsula. Areas where a high density of in situ data is available, including King George VI Sound and the high south central plateau part of the peninsula, show a high spatial variability of net surface mass balance, suggesting that local orographic features play a major part in dictating the mass balance.