'Swati', who was 20 years old, died yesterday, officials at Assam state zoo-cum-botanical garden said.
"Swati was the oldest living tigress in captivity. She was not well for the past few days and was under special care. She had also lost weight," an official claimed.
She was born in 1997 and would have turned 21 in January next year.
The tigress was shifted to Guwahati in 2005, after which she gave birth to six cubs.
She had given birth to five cubs in Mysore zoo prior to her coming to Assam, the officials said.