This study reviewed 20 cases of extensive squamous carcinoma in situ of the vulva and posterior perineum. Two patients had concurrent, overt invasive carcinoma of the vulva, 14 patients had concurrent extensive vulvar carcinoma in situ, three patients had previous skinning vulvectomy for carcinoma in situ, and one patient had prior treatment for invasive vulvar cancer. Six patients had microinvasive carcinoma in the perianal region, which was unsuspected in five of the women. Nineteen of the 20 patients had involvement of the anal canal, and eight patients had disease extending to, or above, the pectinate line. Nineteen patients were managed by regional resection of the involved perianal/anal skin and mucosa with split thickness skin graft. Routine resection of the anal mucosa to the pectinate line was performed, with margin checks when there was dysplasia in the anal canal. The only noteworthy, long-term adverse effect of resecting the anal mucosa and replacing it with a split thickness skin graft was occasional incontinence of flatus in three of the 19 patients. The skinning procedure with split thickness skin graft produced excellent functional and cosmetic results.