The series, which has been subject of a major marketing campaign, is a modern day take on the mythology surrounding Dracula and the Van Helsing family and stars Phil Glenister, Mackenzie Crook and Christian Cooke. Episode one, shown at 7.20pm last night, drew a solid 5.75m (24.1%) over 60 minutes.
In September 2008, the launch of BBC One's new fantasy drama Merlin managed 6.65m (30%), while in January 2007, ITV's similarly-themed Primeval debuted to 6.7m (29%).
Demons successfully defeated the first episode of Your Country Needs You, the BBC's search for an act to represent the UK at this year's Eurovision contest. It pulled in 4.9m (21%) over an hour from 7.10pm.
The most-watched programme of the day was Total Wipeout, a new physical gameshow fronted by Richard Hammond that managed 6.45m (29.4%) from 6.10pm.
ITV1's coverage of the third round FA Cup game between Preston North End and Liverpool averaged 4.72m (23.3%) between 4.45pm and 7.20pm.
After Demons, ITV1's audience took a tumble. All Star Family Fortunes had 4.21m (17.6%) unntil 9.05pm, then a celebrity edition of Who Wants To Be A Millionaire? put in 4.12m (17.3%).
BBC One had a strong 5.8m (24.2%) for National Lottery: In It To Win It, then at 9pm, Casualty interested 5.94m (24.6%).
Overall BBC One had the edge over its commercial rival in primetime with an average share of 21.5% (last week: 23.1%) to ITV1's 20.2% (17.7%).
A network outing for the BBC Scotland series A History Of Scotland brought in a healthy 2.3m (9.6%) for BBC Two in the 8pm hour, then a rerun of Michael Palin's Around The World In 20 Years delivered 1.41m (5.9%).
On Channel 4, a repeat of the documentary The Lost Pyramid - about the possible unearthing of a fourth great pyramid at Giza - picked up 1.03m (4.3%) between 7.25pm and 9pm. The latest edition of Celebrity Big Brother followed with a reasonable 2.72m (11.3%).
Five had 1.3m (5.4%) and 1.39m (5.8%) for an NCIS double-bill from 7.55pm, then a CSI double-bill claimed 1.5m (7.1%) and 1.12m (7.6%).
BBC Two had an average share of 7.8% (9.5%) for third place in primetime, followed by Channel 4 on 7.1% (7.1%) and Five on 5.7% (5.5%).
The largest multichannel audience of the day was 1.17m (5.6%) for BBC Three's screening of Pirates of the Caribbean: The Curse Of The Black Pearl from 8.20pm.
ITV3's double bill of Poirot also proved popular, drawing 566k (2.8%) at 5.55pm then 631k (2.9%) at 8pm.
Ratings data supplied by Attentional