Loquat (Eriobonya japonica Lindl) is a traditional Chinese medicinal plant that contains triterpenes, which have been shown to exhibit pharmaceutical activities. In this study, we investigated various different culture conditions for cultured cells of loquat to produce triterpenes, including illumination, carbon source, nutrient composition and culture system. When cultured on 2.5 mg/l of 6-benzyladenine, 1 mg/l of naphthalene acetic acid and 30 g/l of sucrose at 25 +/- 2 degrees C in the dark for 30 days, the nutrient composition significantly regulated the cell growth and triterpene production. Supplied with the Murashige and Skoog medium reached higher level of dry weight (1.27 +/- 0.09 g per flask) and total triterpene production (151.54 +/- 12.58 mg/g of cultured cells), and the N6 medium produced tormentic acid but inhibited other triterpene products, while the B5 medium produced relatively high corosolic acid. Also found, suspension cultures of loquat cell could achieve high productivity as callus culture. (C) 2010, The Society for Biotechnology, Japan. All rights reserved.