In recent years attention has been called to cases of pyoderma gangraenosum characterized by suppurative destruction of the skin in association with infections of long duration elsewhere in the body. Ulcerative colitis is internal, chronic and debilitating, gives rise to poor resistance and bears a definite etiologic relation to the disease. Ungual changes in association with pyoderma gangraenosum have apparently not been reported in the literature. It is assumed that they are the result of pyogenic infection of the skin which is able to superimpose itself on existing constitutional debility, as well as of lowered resistance of the skin and nails. In the case to be reported here it was noted that dystrophic changes of all the nails took place. The underlying debility was probably responsible for the lowered resistance of the nails. The etiologic organisms found in the skin and stools and repeatedly reported are the hemolytic streptococcus, Staphylococcus