The impressive running of James Simpson-Daniel set Gloucester on their way
Gloucester outclassed Agen with an attractive display in their final pool match but still failed to qualify for the European Challenge Cup last eight.
Their remote chance rested on bottom side Rovigo beating La Rochelle, but the French club cruised to a 71-17 win.
Nevertheless, a rampant Gloucester side - inspired by Freddie Burns and James Simpson-Daniel - racked up five tries to lead 41-0 before half time.
Agen did manage seven points, but the hosts ran out easy winners.
Gloucester finished second in pool five on 21 points, six points ahead of Agen but two points behind group winners La Rochelle while Italian club Rovigo ended bottom without a point to their name.
Simpson-Daniel - who has 10 England caps to his name but has not featured for his country since May 2007 - went over for the first score within 40 seconds after making the most of a two-on-one.
Burn confidently kicked the points, as he did with another seven conversions and penalty, some from tight to the touchline.
The Cherry and Whites moved 20-0 ahead after 22 minutes when Paul Doran-Jones freed Henry Trinder to set up Burns's try.
Burns then returned the favour for Trinder's easy walk-in after the hosts had disrupted Agen's scrum, which was creaking after a series of injuries and knocks to their pack.
Trinder grabbed his second when the video referee eventually ruled that he grounded the ball out wide before his left leg touched the line, though Eliota Fuimaono-Sapolu was then denied by the official in the stands because of a double movement.
However they did not have to wait long for their next score with Tom Voyce powerfully bundling his way through just before half-time.
A clever little kick over the top from the visitors caught the hosts by surprise before Jean Monribot shimmied his way through for Agen's only try, with Conrad Barnard converting.
Trinder then created a lovely angle for Olly Morgan to touch over before captain Luke Narraway rounded it off with an eighth try as Gloucester finished with a flourish.
Gloucester head coach Bryan Redpath told BBC Radio Gloucestershire: "First 40 minutes I was especially happy with - I thought their execution, their intensity, their defensive discipline, their willingness to go out and win this game from the start was outstanding."
"The second half was always going to be tougher, at 41-0 at half time it was going to be a tough second half and just due for the mental side and there was a couple of little mistakes in there - these things happen, but the first 40 minutes I was delighted."
Gloucester: Morgan, Simpson-Daniel, Trinder, Fuimaono-Sapolu, Voyce, Burns, R. Lawson, Wood, S. Lawson, Doran-Jones, James, Brown, Buxton, Qera, Narraway.
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