Hair morphology is one of the most conspicuous features of human variation. The hair follicle has attracted significant attention as a model for the investigation of diverse biological problems. Whereas, very little is known about the genes influencing the morphology and structure of the hair shaft. Curly hair is very common character of hair phenotypes of human, while most congenital curl occurs owing to genetic factors and some are closely related with genetic diseases. This review highlights current related genes reported affecting hair curliness and human diseases which are due to gene mutations.