The character of Jessica Van Helsing was originally written to be the daughter of Professor Van Helsing. However, the death of Peter Cushing's wife aged him considerably, so the script was quickly re-written to make him Jessica's grandfather.
The film was inspired by the story of the Highgate Vampire, a media sensation surrounding reports of supposed supernatural activity in Highgate Cemetery in London in the early 1970s.
A picture of Peter Cushing's recently deceased wife Helen Cushing can be seen on the desk in Professor Lorrimer Van Helsing's study.
The film was released only two days before El expreso del horror (1972), which likewise starred Christopher Lee and Peter Cushing.
Dracula's taunting of Van Helsing in the church ("You would play your brains against mine, against me who has commanded nations?") directly references Dracula's dialogue from Bram Stoker's novel: "Whilst they played wits against me, against me who commanded nations, and intrigued for them, and fought for them, hundreds of years before they were born, I was countermining them."