An Eastern Airlines night ticket agent was stabbed early yesterday when he surprised two men who were robbing the airline's office at National Airport, a Federal Aviation Administration spokesman said.

Although the stabbing occurred near a waiting area where at least 25 people were seated at the time, the wounded agent, Ignatius Martin, 39, was not discovered for almost an hour, the spokesman said.

Martin found the men in an office behind the airline's ticket counter in the main terminal when he returned from a break about 2:20 a.m., the spokesman said, and was stabbed in the back and tied up. His assailants escaped with an undisclosed amount of money.

It took Martin almost an hour to make his way to a door to call for help, according to the spokesman.

Martin was taken to the National Hospital for Orthopaedics and Rehabilitation in Arlington with a three-inch portion of a knife blade lodged in his lower back, the FAA said. Initially his condition was reported as critical, but last night, after surgery, he was said to be in good condition.

The FBI is investigating because the stabbing occurred on federal property.

Sam Walker, an Eastern Airlines manager, described Martin, who lives in Fort Washington, as "an excellent employe."