Woolly hair is a unique hair phenotype, which is characterized by extremely curly hair. While this type of hair is common in black people, it is extremely uncommon in non-blacks. When woolly hair appears together with thickening of the skin of the palms and soles, it should immediately raise the concern of Naxos or Carvajal syndromes, which are characterized by life-threatening cardiomyopathy, and should necessitate immediate referral to cardiac evaluation. The factors which control hair curliness are still obscure, but it is thanks to the recent discovery of the genes responsible for some of the woolly hair syndromes that these factors start to reveal. In this review we provide summary of the cell structures and factors which control woolly hair, and provide a unifying mechanistic pathway for the control of hair texture. Furthermore, this review provides an algorithm for directing the diagnosis of the patient with woolly hair. (By Dr. Yuval Ramot, http://jmg.bmj.com/content/early/2015/01/05/jmedgenet-2014-102630 )