Fox’s critically heralded drama “House” took shelter behind “American Idol” Tuesday night and emerged much stronger in the ratings.

According to Nielsen, the rookie medical mystery series easily delivered its best ratings to date Tuesday (5.0 rating/12 share in adults 18-49, 12.37 million viewers overall), winning the 9 o’clock hour for the first time.

Although “House” retained less than half of its not-too-compatible lead-in from “American Idol” (12.1/31 in 18-49, 28.06m), Fox will certainly take these results as it looks for more solid performers to add to its sked.

Net must also be encouraged by the younger viewers that “Idol” brought to “House,” although the Hugh Laurie-led procedural remains more of a draw among the 18-49 and 25-54 set (5.6/12) than in 18-34 (4.2/11) or teens (2.9/9).

“Idol” was huge again at 8, topping the combined deliveries of the other five broadcast nets by 16% in 18-49 (12.1 vs. 10.4). It was down a bit in the demo from the same night a year ago (13.0) but up vs. 2003 (11.6).

Other top performers on the night were NBC’s “Law & Order: SVU” at 10 (5.4/14 in 18-49, 14.19m), CBS’ “Amazing Race 6” at 9 (4.7/11, 12.03m) and ABC’s “According to Jim” (4.2/10, 10.81m), also at 9.

Also of note was a solid showing by the WB’s drama duo of “Gilmore Girls” (2.3/6 in 18-49, 5.05m) and “One Tree Hill” (1.7/4, 4.07m), which aired their first new episodes since November. Compared with the same night a year ago, both shows were up more than 20% in persons 12-34.

Not looking so good were NBC’s middle-hour comedy combo of “Scrubs” (3.1/7 in 18-49, 7.02m) and “Committed” (2.7/6, 6.17m).