We report a case of a seven months old female patient with diagnosis of generalized primary elastosis or cutis laxa, that also presented a posterior perineal hernia; it was treated with surgery (abdominal and perineal) and the postoperatory evolution was favorable. In the literature it had been reported around 100 cases of posterior perineal hernia; but most of them occurred in adults patients of the female sex, with a high proportion of pregnancy or as a result of radical cancer surgery like pelvic exenteration. This is the first case of posterior perineal hernia in the Hospital Infantil de Mexico Federico Gomez and the third founded in pediatric age in the literature.