This film, which is identical with "Hansel & Gretel" (which is listed in the IMDb as a different movie), is one of five films Lucio Fulci "presented" and "supervised" towards the end of the 1980s (the others are "Non Avere Paura Della Zia Marta" aka "The Murder Secret", "Snake House" aka "Bloody Psycho", "Massacro" and "Fuga Dalla Morte" aka "Luna di Sangue"). From these four films, Fulci later used most of the gore effects again in his "Un Gatto nel Cervello" aka "Nightmare Concert".
The idea is a good one: Two children get abducted by villains who take their organs to sell it illegally for transplantation. The ghosts of the kids return and take revenge, forcing the bad folks to suffer more or less nasty deadly accidents. The problem is that Giovanni Simonelli brought too much insignificant dialogue into this film, so it early loses most of its pace and goes on rather slowly. The budget obviously was quite low, therefore, even though the villains suffer mostly ghastly demises, only few of them are really gory (especially an accident involving the victim's eye, which is the only scene Fulci used again for "Nightmare Concert").
Although the film isn't really good, it's still quite interesting and entertaining, mainly because of the good idea. I just don't understand why this film never was released even in Italy (the same fate suffered "Fuga Dalla Morte", while "Snake House" got a release in Italy and Germany, "Massacro" at least in Germany, and "The Murder Secret" in France), because compared to many other (mostly direct-to-video) low budget horror, "Non Si Seviziano i Bambini" is an okay film.