David Slade's directorial follow-up to the acclaimed Hard Candy is based on the graphic novel about an Alaskan town whose proximity to the North Pole plunges it into total darkness for one month, rendering it the perfect playground for vampires.
John Hartnett provides the heroics alongside Melissa George. Danny Huston and Ben Foster also star.
30 Days' promising debut meant that the films' sales agent, Mandate International, could claim the top two spots at the North American box office this weekend. Mandate was recently bought by Lionsgate for $56m.
There were three other new releases this weekend, led by Miramax's crime drama Gone Baby Gone directed by Ben Affleck and starring his brother Casey Affleck, Michelle Monaghan and Ed Harris. The Dennis Lehane adaptation ranked fifth on $6m.
Fox's sports comedy The Comebacks - the second film about American football after The Game Plan to enter the top 10 in recent weeks - launched in sixth place on $5.9m. It stars David Koechner and Carl Weathers.
New Line's terrorism drama Rendition, Gavin Hood's directorial follow-up to his Oscar winning Tsotsi, debuted in ninth place on $4.2m. Reese Witherspoon, Jake Gyllenhaal, Omar Metwally and Yigal Naor star, with a supporting role from Meryl Streep.
Tyler Perry's Why Did I Get Married had sufficient momentum to stay above most of the competition as it fell one place to second on $12.1m for a $38.9m tally in its second weekend.
Similarly, Buena Vista's The Game Plan ranked third on $8.1m and has amassed an impressive $69.2m after four. Warner Bros' legal thriller Michael Clayton benefited from ongoing strong word of mouth to anchor itself in fourth place with a collective $21.9m after three weekends.
DreamWorks-Paramount's drama Things We Lost In The Fire, Danish director Susanne Bier's first English-language film, launched in 15th place on $1.6m. Benicio Del Toro and Halle Berry are the stars.
In limited release, Control, Anton Corbijn's drama about the late Joy Division frontman Ian Curtis, raised its tally by $36,000 from two screens in Los Angeles and New York to $91,000. The film, released in the US through The Weinstein Company, expands into the 10 markets this week.
Next weekend's wide releases are: Lionsgate's Halloween horror staple Saw IV with Tobin Bell; and Buena Vista's comedy counter-programmer Dan In Real Life starring Steve Carell and Juliette Binoche.
Estimated Top 10 North America Oct 19-21, 2007
Film (Dist)/Int'l dist/Est wkd gross/Est total to date
1 (-) 30 Days Of Night (Sony) Mandate Int'l $16m -
2 (1) Why Did I Get Married' (Lionsgate) Mandate Int'l $12.1m $38.9m
3 (2) The Game Plan (Buena Vista) WDSMPI $8.1m $69.2m
4 (4) Michael Clayton (Warner Bros) Summit Int'l $7.1m $21.9m
5 (-) Gone Baby Gone (Miramax) WDSMPI $6m -
6 (-) The Comebacks (Fox) $5.9m -
7 (3) We Own The Night (Sony) Wild Bunch $5.5m $19.8m
9 (-) Rendition (New Line) NLI $4.2m -
10 (5) The Heartbreak Kid (DreamWorks-Paramount) PPI $3.9m $32.1m