Two cDNA clones encoding two different beta-tubulins, RTUB-1 and RTUB-2, were isolated from a rice cDNA library and their nucleotide sequences were analyzed. The deduced amino acid sequences showed amino acid sequence identity between 92% and 97% with other plant beta-tubulins. Southern blot analysis using gene-specific and coding-region probes suggested that beta-tubulins in rice are encoded by multigene families. The two cDNA clones represent two subfamilies of rice tubulins, RTUB-1 and RTUB-2, consisting of 3 to 4 genes and a single gene, respectively. The transcript levels of RTUB-1 and RTUB-2 genes were higher in actively elongating tissues such as etiolated shoot tissues and light-grown root tissues of four-day old seedlings.