Leaf is an important organ for photosynthesis. Moderate leaf rolling could facilitate structure improvement of plant population and enhance light-use efficiency, which is important in breeding for ideotype plants. A rolled leaf mutant temporarily named rl12(t), was obtained from the rice ( Oryza sativa L.) restorer line Jinhui 10 treated with ethyl methyl sulphonate (EMS). In the mutant, the newly developing leaves of the mutant did not roll, the upper 1/3 section of mature leaves was curled, and the older mature leaves were rolled completely. The pigment contents of the mutant increased significantly. The cytoplasmic male sterile (CMS) line Xinong 1A with flat leaves was crossed with the rl12(t) mutant to produce F 1 and F 2 populations. Genetic analysis indicated that the mutant was controlled by a single dominant gene. Gene rl12(t) was finally located on chromosome 10 between SWU-1 and SWU-2 with the genetic distances of 1.5 and 0.2 cM, respectively. Because no genes for rolled leaf trait have been previously located on this chromosome, RL12(t) should be a novel and unique dominant gene for rolled leaf.