Alton, trailing 15-0 at half-time, fought their way back to within a point of Old Guildfordians, but just could not force the winning score.
And it was a game Alton were desperate to win against the division's bottom side who have had points deducted.
Although Alton's Anstey Park pitch is renowned for its pronounced slope, the incline at Stoke Park, Guildford leaves it in the shade.
Alton were unlucky enough to have to play up the pronounced hill in the first half, but it was lacklustre defence that cost them a converted try within three minutes.
A further try and a penalty extended the lead to 15 -0 after 25 minutes.
At this point, Alton seemed to realise that Guildfordians were beatable and, in tightening up their defence, stifled the home side.
Early in the second half, now playing downhill, Alton forced their way into the corner and stand-off Lee Howard finished off the move by scoring beneath the posts, David Rowledge added the conversion.
Alton kept up the pressure and eventually forced their way over again. This time, hooker Jon Green, in his first senior game of the season, grounded the ball and again Rowledge converted, narrowing the deficit to just one point.
But the match then deteriorated into a mid-pitch stalemate, with both teams making a series of mistakes.
Rowledge was unlucky five minutes from time when his 45-metre penalty attempt crept just underneath the crossbar.
Alton are home to Maidstone in the league this Saturday.