The deal's financial terms were not disclosed.
Symantec said in a statement that the increased use of IM in the corporate world was an impetus for the acquisition.
"Real-time communication solutions like instant messaging are powerful collaboration tools that create a new attack vector for threats to enter an enterprise network and new forms of digital communication with the same government, legal and business requirements to retain and retrieve as email," said Enrique Salem, senior vice president of security products and solutions for Symantec.
A link on the IMLogic website referred users to Symantec's statement. The companies had previously partnered to provide IM security solutions, and researchers from the two firms had also collaborated.
Francis deSouza, president and chief executive officer of IMLogic, said his customers have been using products from both companies.
"Our customers have asked us for a holistic management tool to control all real-time collaboration and keep it highly available, compliant and secure," he said. "They understand the requirements for messaging security and a number of them are already using our solutions with Symantec solutions."
Symantec also kicked off 2005 with a major business decision, merging with Veritas in a $13.5 billion all-stock deal.
IMLogic's competitor, Akonix, said in a statement that it believes the acquisition is proof IM security will continue to grow.
"Some companies are now spending a lot of money on instant messaging security," he said. "Many of the same kinds of vulnerabilities that are susceptible through email are susceptible through instant messaging."