A 1-kestose-producing fungus, strain N-01, was isolated and identified as Scopulariopsis brevicaulis. The optimal conditions for 1-kestose production by strain N-01 were studied and the following conditions were established : the strain was cultivated in a 500-ml conical flask containing 25 ml of medium composed (per liter) of 150 g sucrose, 15 g yeast extract, 0.6 g urea, 1 g K2HPO4, and 0.3 g MgSO4.7H(2)O (pH 7.0) at 30 degrees C for 72 h. When the strain was cultivated in a 2.5-l jar fermentor, 95 g of 1-kestose was produced with a theoretical yield of 85%. From this culture broth 1-kestose was crystallized and then recrystallized, giving purities of 98.0 and 99.8% with yields of 71.0 and 78.0%, respectively. In particular, the first crystals in the recrystallization gave over 99.9% purity. By using these crystals, the general properties of 1-kestose were determined; most of these properties coincided with the data in the literature, though the melting point range was narrower. Finally a scheme for the large-scale purification of 1-kestose is proposed.