The dry matter degradation in a cellulase-buffer solution of the whole straw of six Malaysian rice varieties was estimated before and after treatment for 21 days in a 4% urea or 4% sodium hydroxide (NaOH) solution. Degradation characteristics were estimated from the equation p = a + b (1 - e^-ct). Both urea and NaOH treatment significantly increased the rapidly degradable (constant a) and slowly degradable (constant b) fractions. The degradation rate (constant c) was significantly reduced by urea treatment but not by NaOH treatment. The degradation constants were independent of the agronomic and morphological characteristics of the untreated straws.