A new mutation was identified in the PD (Preaxial Duplication) strain of rats, the main manifestations of which were and sparse with retarded outer hair growth. As the main characteristic of this mutant rat is abnormally curled appearance of the vibrissae, curly vibrissae is proposed as the name of this mutant gene, and as its symbol. Genetic analyses reveal that the mutant characteristics are inherited as autosomal recessive traits and the cv gene is independent from the pd gene that carried by the original PD colony. The cv/cv homozygous rats have a small number of short and/or around the nose. The on the cheek and/or above the eyes are also short and curled; however, no vibrissa appears on the lower mandible. Although hair growth seems to be retarded, the outer hairs showed nearly normal length by 10 weeks of age. The outer hairs of matured cv/cv rats appear silky and translucent. The adult mutant rats often exhibit loss of hair on the head and/or back. Lactating females usually lose their abdominal hair. Both sexes of cv/cv homozygotes have normal reproductive ability. No internal malformations accompany vibrissa and hair abnormalities.