For the first time, an in vitro regeneration system for `Green Sweet' apple has been developed from nucellus-raised callus. Callus induction (100%) occurred in nucellar explants excised from immature fruit when cultivated on Murashige and Skoog (MS) basal medium, free of plant growth regulators (PGR) and supplemented with 3.0% (w/v) sucrose and 0.8% (w/v) agar. When cultured on MS basal medium supplemented with 10.0 mu M benzyladenine (BA) and 1.0 mu M gibberellic acid (GA(3)), calli showed 88.9 +/- 5.6% shoot regeneration with 4.1 +/- 0.1. shoots per explant, and a mean shoot length of 3.5 +/- 0.2 cm. Elongated shoots produced roots (44.4 +/- 5.6%) when placed in half-strength MS basal medium supplemented with 1.0 mu M indole-3-butyric acid (IBA) and 1.0 mu M a-naphthaleneacetic acid (NAA). Maximum rooting percentage (55.6 +/- 5.6%) was obtained on 0.4% (w/v) agar, while the highest number of roots per shoot (2.8 +/- 0.4 roots) and root length (3.4 +/- 0.2 cm) were recorded on 0.6% (w/v) agar. Acclimatisation of in vitro-raised plantlets resulted in 39.1 % surviving plantlets. The findings of this study indicate that nucellus-raised callus of the apple cultivar `Green Sweet' can efficiently regenerate shoots that can be rooted and successfully acclimatised.