Willie poaching was the tormentor in chief with a second-half hat-trick of tries as Leeds made the gap between the top and the bottom of Super League look every bit as big as it is.
A convincing victory restores the Rhinos' five-point lead over the chasing group and leaves Castleford four adrift at the foot of the table.
Castleford started their first match since the departure of their high-profile coaching consultant, Ellery Hanley, amid rumours that their head coach, Gary Mercer, would be the next to go. The heavy defeat only threatens to speed that process.
After only two minutes, Dean Ripley lost Kevin Sinfield's high kick for Marcus Bai to touch down the loose ball and the Rhinos were on their way.
Danny McGuire had never failed to score a try in five previous games against Castleford, but he had never got one from as far out as his ninth-minute effort last night. Taking Chev Walker's pass, he went 90 yards for his 23rd in Super League so far.
Mark Calderwood had a try disallowed for a forward pass from Walker and Cas did well not to concede further points, even applying pressure of their own, culminating in Andy Lynch's try.
Unfortunately, Wayne Godwin's conversion attempt barely got off the floor. Even worse, Nathan Sykes immediately knocked on under his own posts and Matt Diskin scored from Sinfield's pass.
From the kick-off, Francis Cummins and Jamie Jones-Buchanan made the initial inroads to send Maguire away for his second.
Poaching went over within 30 seconds of the restart and then set up Calderwood for Leeds' sixth try, before McGuire's vision presented Poaching with his second, with Sinfield missing his shot at goal for the only time of the evening.
Craig Greenhill got one back for Cas, but Poaching was irrepressible, and claimed his third try after a spell of sustained pressure.
The previously quiet Motu Tony went the length of the field for a late consolation for Castleford. They might have taken more comfort from the way that they had not quite been thrashed as badly as had sometimes seemed likely.
Leeds: Cummins, Calderwood, Walker, Senior, Bai, McGuire, Dunemann, Feather, Diskin, McDermott, McKenna, Adamson, Sinfield. Substitutes: Burrow, Poching, Jones-Buchanan, Ward.
Castleford: Gibson, Ripley, Tony, Rogers, Mellor, Davis, Robinson, Greenhill, Hudson, Sykes, Smith, Harland, Clayton. Substitutes: Lynch, Godwin, Saxton, Hepworth.
Referee: A Klein (London)