The objective of the present study was to determine sugar and dietary fiber contents in 37 varieties of Thai fruits. Sugars were determined by high-performance liquid chromatography and dietary fiber values were measured by the enzymatic-gravimetric method. The total sugar (sucrose, fructose and glucose) content ranged from 4.5 g/100 g (strawberry) to 20.3 g/100 g (ripe banana; hawm variety) edible portion. All varieties of ripe banana provided good sources of glucose, fructose and total sugar. The total dietary fiber content ranged from 0.6 g/100 g (watermelon) to 11.5 g/100 g (sapodilla) edible portion. The rank of TDF contents per 100 g edible portion was sapodilla > durian > guava and strawberry > apple > Chinese pear > sugar apple > star fruit. Other fruits contained total dietary fiber values lower than 2.4 g/100 g edible portion, especially watermelon, which had the lowest total dietary fiber content (0.6-0.7 g/100 g edible portion).