The 84-year-old man suffered life-threatening injuries, according to Golder Ranch Fire Battalion Chief Will Seeley, who had no other details on his condition.
The man was attacked Wednesday by a hive located in a shed behind his Oro Valley home. There were close to 50,000 bees inside the shed.
He was then taken to Oro Valley Hospital, where he was talking and breathing on his own at the time, Seeley said.
The man sustained close to twice the lethal dose of bee venom, doctors reported.
Neighbors say they had noticed an unusual amount of bees earlier that day.
Calls to the fire department for help with swarms of bees are common, Seeley said.
The hive has since been removed.