Fifty-three king cobras were seized by Hoang Mai District police and environmental officers in one incident Friday, and 56 more were found in a car in Hanoi and seized later in the day, the Vietnam News Agency reported Monday.
Vietnam prohibits the trading of cobras for commercial purposes.
Officials said they are working to curb the country's wild animal trafficking, after a survey indicated a robust Internet market.
The survey, released by the Wildlife Conservation Society at a conference in Hanoi last week, said up to 108 wild animal species were found to be sold illegally on 33 Vietnamese websites.
Scott Robertson, director of the society's Vietnam office, said snakes, iguanas and crocodiles were found for sale, as well as monkeys, elephants, squirrels and tigers.
The survey said 24 percent of Vietnam's wild animals are protected by law, another 24 percent are banned from sale by the international Convention on International trade in Endangered Species of Wild Fauna and Flora, and 17.6 percent are listed under the global endangered species list.
It added 84 percent of illegally trafficked animals are sold as pets, 9 percent for food and 1 percent for medicine processing.