Jorge Grau's "Ceremonia sangrienta" (called "The Legend of Blood Castle" in English) is one of many movies telling the story of sixteenth century Hungarian countess Erzsebet Bathory, who reportedly bathed in the blood of young virgins so as to maintain her youth and beauty. This one has less nudity than I've come to expect in Euro-horror flicks; I think that they wanted to focus on the plot more than anything, and they did a worthwhile job. The nude scenes, so to speak, are the scenes where she lets the blood run all over her body.
The only other Erzsebet Bathory movie that I've seen is "Countess Dracula", which I thought was worth seeing (although it was more of an excuse to show off Ingrid Pitt). This one stars Lucia Bose, Espartaco Santoni and Ewa Aulin. Aulin is best known as the title character in Christian Marquand's 1968 psychedelia-fest "Candy". She starred in a cinematic acid trip and in a movie about a sicko countess. Whoa...
Anyway, worth seeing. You may find it under a different title, as often happens with Euro-horror flicks.