Launceston twice let leads slip as they went down 27-25 at Hartpury College in National Two South.
The Cornish All Blacks led 20-7 after 20 minutes thanks to tries from Richard Bright and Ben Hilton as Kieron Lewitt added 10 points with his boot.
Tries from Ryan Brend and Waylon Gasson helped Hartpury go into a 22-20 lead before James Lightfoot-Brown's try saw Launceston go 25-22 up.
But Brandon Walker got the winning with 12 minutes left for Hartpury.
"Really we wanted more, our target was to win the game," Launceston fly-half Lewis Webb told BBC Radio Cornwall.
"We put ourselves in a position to win the game. But credit to Hartpury, they capitalised on our mistakes and we gifted them a few tries.
"I'm happy with the losing bonus point but we came here for a win really," Webb added.