Toenail blackening has the following situations to consider: 1, if through the hard, too tight shoes, or too much exercise, toenail was smashed and other trauma, will lead to bleeding under the toenail, the toenail also looks purplish-black, touching the toenail will have pain. At this time usually do not need special treatment, slowly will be absorbed.2, nail fungus sometimes also have brown-black performance, at the same time the toenail will also have other manifestations, including toenail thickening, deformation, brittle crack, peeling, etc., check the fungus to help diagnosis.3, toenail pigmentation black streaks, at this time, need to be further examined, in order to rule out the possibility of undesirable lesions. Therefore, the toenail turns black, depends on the specific blackening situation, need to be examined by a clinician to give diagnosis and treatment.