TR21, an original tanshinone IIA-producing endophytic fungus from the root of Salvia miltiorrhiza Bunge, produces low levels of tanshinone IIA. Three techniques were used to rapidly improve tanshinone IIA production: TR21 mutation by ultraviolet radiation (UV), TR21 mutation by sodium nitrite (NaNO(2)) and TR21 mutation by a combination of both UV and NaNO(2). An improved mutant, labeled as NU152, was obtained from the combination of UV and NaNO(2). The content of tanshinone IIA produced by NU152 held a relative high value of 51.44 +/- 0.22 mu g per g, and the NU152 produced a more than 1.46-fold increase in tanshinone IIA yield, compared with the wild type TR21 (P < 0.05). The fungus NU152 showed a possible way for the sustainable production of tanshinone IIA. (C) 2011 Elsevier Ltd. All rights reserved.