Callus derived from mature seed scutella of Oryza sativa L. cv. Taipei 309 was initiated on LS medium (Linsmaier and Skoog, 1965) semi-soli- dified with 0.4% (w/v) Sea Kern agarose (Flowgen Ltd., Shenstone, UK) and supplemented with 2.5 mg 1~ ’ 2,4-dichlorophenoxyacetic acid (2,4-D). This callus was used to initiate cell suspensions which were maintained by sub-culture every 7 d in The protoplast plating efficiency of this, and other economically-important cereals, is still low when compared to the generally more efficient proto- plast systems of their dicotyledonous counter- parts. Abdullah et al. (1986) reported that while initial division occurred in up to 57% of cells derived from cultured protoplasts isolated from several varieties of Japonica rice, only ca. 1% of such protoplasts underwent sustained mitotic divi- sion leading to visible cell colonies. The results obtained using rice protoplasts are dependant on a number of variables, primarily the source mate- rial and plant genotype. At present, embryogenic cell suspensions are the prime source material for the isolation of totipotent rice protoplasts. How- ever, as well as the choice of plant variety, source material and culture medium used, additional in- novative approaches are also required to elevate rice protoplast systems, in terms of their plating efficiency, to levels more comparable to those of dicotyledons.