Debate over a forestry incentive scheme in the Gisborne district, New Zealand, highlighted the need for up to date information on the vegetation cover. Maps of vegetation at a scale of 1:100 000 were produced by automatically classifying Landsat Thematic Mapper (TM) imagery. The classified imagery was compared with existing vegetation information (20-years-old) from a GIS database to identify gross errors. Through field checking the discrepancies were identified as either real changes or errors in classification. Correction of errors increased the overall classification accuracy from 84 to 90 per cent.