A 60-year-old former treasurer of the West Norfolk and Wisbech branch of Unison has admitted stealing £12,000 from the union.
Ronald Glazebrook, of Burch Close, King's Lynn, admitted theft between February 2006 and October 2007.
At Norwich Crown Court, Glazebrook was given a 10-month sentence, suspended for two years.
The thefts involved the subscriptions from members at the local hospital, the court was told.
The thefts were discovered when a new person took over the running of the branch.
It was discovered more than £9,000 of cheques had been signed by Glazebrook including payment for caravan sites, a holiday cottage and kennels.
Glazebrook was arrested and it was established he had stolen more than £12,000.
Katherine Moore, representing Glazebrook, said it was a breach of trust but his client had admitted the offences promptly.
"The money will be paid back. He (Glazebrook) did not take up the position with the intention of becoming dishonest," she said.
She said Glazebrook was seriously ill.
Recorder Michael Evans said he had given him a suspended sentence because of his ill health.