Peristomal skin lesions in patients with ileal conduit urinary diversion have been reported in frequencies ranging from none to occurrence in 100% of patients. In previous studies skin lesions often are referred to in unspecific terms, which has made it impossible to compare results with those of other studies. Thus a classification of peristomal skin (CPS) has been developed on the basis of macroscopic peristomal findings. It defines what can be accepted as ordinary findings, as well as two different types of skin lesions, erythematous-erosive and pseudoverrucous. Each of these is divided into two subgroups. Such a classification is a prerequisite for a meaningful comparison of the type, incidence, and severity of skin lesions in different groups; it also may allow a more reliable clinical evaluation of new ostomy appliances and skin care products. In addition, CPS may also facilitate communication among professionals who are responsible for the care of ostomy patients.