The mutants involved in the development of floral organ are good material for understanding the molecular genetic mechanisms of floral development. A rice mutant, that lacks palea in its florets, was derived from a spontaneous mutation in an indica line, SAR III-93-369. Genetic analyses in three F2 populations from the mutant crossed with three rice varieties, Sheng 47, N625 and CDR22, respectively, showed that the mutant trait is controlled by a single recessive gene. In the F2 population from npa-1/Sheng47 the gene for the non-palea trait was mapped between two restriction fragment length polymorphism markers, C498 and RZ450, with distances of 7.5 cM and 2.4 cM, respectively. The tagged recessive non-palea gene is temporarily designated npa-1.