Similarly, use of NAA in combination with BA was needed in in vitro culture of Aranda (Lakshmanan et al. 1995) and Dendrobium (Sinha et al. 2003). In the present study we have optimized BA-NAA combination, and obtained the highest number of PLBs in leaf explants of Phalaenopsis amabilis cv. 'Golden horizon' cultured on ½ MS medium supplemented with 2.0 mg l-1 BA and 0.5 mg l-1 NAA along with 2% (w/v) sucrose, 10% CW, 2 g l-1 peptone and 1 g l-1 activated charcoal. In another experiments on leaf cultures of Phalaenopsis, 3% sucrose was used (Tanaka and Sakanishi 1977, 1980, Haas-von