This was the second year the Hugos were presented, and again there was no shortlist of nominations but there was a vote of the membership to select the winners. (See Early Hugo voting.) The Clevention committee significantly changed the Hugo categories from those inaugurated by Philcon II in 1953.
The somewhat odd result for Best Novel was apparently due to a bloc vote by Astounding readers who were appalled that a Galaxy (not really an sf magazine at all. Hmmph) did so well, tieing ASF for Best Prozine and doing well in other categories as well.. Since there were so few voters in those days, they were successful.
1955 Best Novel Hugo: They'd Rather Be Right by Mark Clifton and Frank Riley
1955 Best Novelette Hugo: "The Darfsteller" by Walter M. Miller, Jr.
1955 Best Short Story Hugo: "Allamagoosa" by Eric Frank Russell
1955 Best Professional Magazine Hugo: Astounding Science Fiction ed. by John W. Campbell, Jr.
1955 Best Professional Artist Hugo: Frank Kelly Freas
1955 Best Fanzine Hugo: Fantasy Times ed. by James V. Taurasi, Sr. and Ray Van Houten