Mike Foley's side were undone by an impressive first half performance by the Saints which saw former England full back Nick Beal contribute heavily to three tries, one for Oriol Ripol and a brace for Peter Jorgensen.
However, despite creating opportunities and dominating in the scrum, Bath Rugby were unable to capitalise on good field positions and had just one Olly Barkley penalty in the first half to show for their efforts.
The second half saw a much more resolute performance by Bath Rugby, but despite setting up camp inside the Saints 22 on several occasions, the visitors were unable to break a determined Northampton defence.
Indeed any chance of a second-half fight back was quashed when Mike Tindall was shown the yellow card for deliberately 'slapping down' a Peter Jorgensen pass. It was a close call by referee McHugh, who had earlier let a similar action go unpunished earlier in the half (ironically from a Tindall pass).
Against 14 men in the final ten minutes, the Saints looked to take advantage of the natural overlap in the backs. However, it was not until the 78th minute when Bath's stalwart defence finally cracked as Nick Beal worked Ben Cohen over in the corner for the only score of the second half.
