At an industry conference in San Francisco, an audience member asked the Oracle cofounder what to tell potential Oracle cloud-computing clients who worry that the National Security Agency could access their information.
"To the best of our knowledge, an Oracle database hasn't been broken into for a couple of decades by anybody," Ellison replied.
"It's so secure, there are people that complain," he added.
Oracle, Salesforce.com and other major Silicon Valley companies are increasingly offering Internet-based business services, like human resources, accounting and sales management, in a trend known as cloud computing.
Entrusting software and data management to cloud services can save companies the expense of maintaining their own servers and other IT infrastructure.
Former NSA contractor Edward Snowden's revelations about U.S. government surveillance have increased companies' concerns about privacy and may cost U.S. technology vendors billions of dollars in lost sales, analysts say.
The roots of Ellison's software company go back to 1977, when the Central Intelligence Agency contracted him and two coworkers to design a database, codenamed Oracle. The same year, Ellison and his colleagues founded the database company that would eventually be renamed Oracle.
In an interview with CBS News' Charlie Rose in August, Ellison said he believed the NSA's widespread surveillance was essential to preventing terrorism.
© Thomson Reuters 2014