Regeneration was investigated in non-sterile leaf explants taken from 87 Begonia lines after culturing for up to 10 weeks in vitro on Knop's mineral salts agar medium with no exogenous growth substances present. For many lines, only very limited supplies of leaf samples were available; nevertheless, in 66 lines de novo regeneration of roots and buds occurred and potted plants were recovered from 49 lines. Additionally in 13 Begonia lines, buds were excised from stock plants and cultured under non-sterile conditions on Knap's agar. In seven of these the buds rooted and gave rise to potted plants. In six lines organogenic cultures (derived from sterile leaf explants) have been established in long-term culture on Murashige & Skoog medium supplemented with growth substances and potted plants have been recovered. Sterile explants from a further 12 lines showed regeneration and have been sub-cultured. The establishment of such sterile cultures, with continued regenerative capacity, is a significant step in the development of a programme for the conservation of rare and endangered begonias.