The development of an efficient micropropagation system for Huang qin (Sculellaria baicalensis Georgi), a traditional Chinese medicinal plant used in the treatment of a wide range of human ailments, is described. Thidiazuron rn [TDZ: N-phenyl-N'-(1, 2, 3-thidiazol-5-ylurea)] effectively induced regeneration on cultured intact seedlings, etiolated hypocotyl explants and sterile stem segments of Huang-qin. Histological examinations of excised hypocotyls or nodal ex plants revealed that the regenerants were primarily shoots formed de novo on an intermediate callus. The comparison of the rates of TDZ-induced regeneration in the three tissue types indicates that the isolation of the explants was not essential for optimal regenerative efficiency. Significantly more regenerants formed on the hypocotyls of intact seedlings (20shoots/explant) than were observed on the excised hypocotyls (9.7shoots/explant) indicating that endogenous metabolites produced in adjacent tissues provided resources for the shoot initiation. More than 95% of de novo regenerants formed roots and then intact plantlets under either sterile culture or greenhouse conditions. The regeneration protocols developed in this study may provide the basis for the improvement and mass micropropagation of this crop.%研究了中药黄芩(Scalellaria baicalensis Georgi)的微繁技术。TDZ[N-phenyl-N'-(1,2,3-thidiazol-5-ylurea)]用于组培中能有效地诱导黄芩完整实生苗、白化下胚轴段和茎段再生新枝。下胚轴段和茎段外植体的组织学研究显示其再生是通过愈伤组织形成新枝。TDZ诱导黄芩3种组培外植体枝再生的比较表明，理想的再生不一定要外植体脱离母体。黄芩完整实生苗的下胚轴上形成的枝明显多于下胚轴段上形成的枝，表明完整实生苗中产生的代谢产物提供枝再生所需的物质。95％以上的再生体形成根系，在无菌培养和温室中可形成完整植株。本研究所采用的再生程序可以用于这种药用植物的改良和大量繁殖
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