This film was originally conceived as a low budget softcore pornography film titled "The Loves of Count Iorga, Vampire". Later, however, the decision was made to film it as a regular horror film with the less erotic title "Count Yorga, Vampire" . This name change explains the poor animation of the name "Count Yorga" in the film's title as it now appears on-screen. The original title and original Iorga spelling were both restored to the film by the 1990s, but all prints of it were still identical to the original 1970 release. Apparently, no additional footage survives from its original porn version of it at all and it is unknown if said version was actually filmed or, if it was filmed, whether or not it was finished or even released if it was (it is worth noting, however, that the characters often pronounce the Count's name within the film as "Iorga" (ee-yor-ga) and not as "Yorga" (yor-ga)).
American International Pictures had planned to revive Count Yorga as an enemy of Dr. Phibes in the film Dr. Phibes Rises Again (1972). While this plan was eventually scrapped, Robert Quarry (who played Count Yorga) did appear in the film as Phibes' enemy, only now this enemy was named Darius Biederbeck. He also went on to costar with Vincent Price and Peter Cushing in Madhouse (1974).
The scene in the film where Erica is discovered to be eating her pet kitten was accomplished by covering a sedated kitten with canned lasagna.
Legendary actor George Macready narrated this film, his son Michael Macready co-starred, and it also features blonde bombshell Erica Macready as the doctor's Swedish nurse, who in real life was married to Michael (and listed as Erica E. Ebeling on his profile here), thus making her George's daughter-in-law.