Shulamit Gershenson was one of the first employees Laura Grimmer hired when Articulate Communications Inc. opened in 2002. When Gershenson left the New York City PR company in 2004, she was the first person Grimmer wanted back.

"I kept her on my mailing list," says Grimmer, 38, the founder and CEO. "We'd get together once a month or so for drinks." Before long, Grimmer started hearing that Gershenson's new job at a non-profit organization wasn't working out. She made sure her ex-employee was invited to the 15-person agency's 2004 holiday party. This got Gershenson thinking about returning to her old job. In April 2005, a year after leaving the $2.2 million company, she returned as vice president.

Grimmer is more than pleased to have Gershenson back onboard. "She has knowledge about the way we work and our clients that is difficult to teach somebody coming in at the senior level," Grimmer explains.

If you're not mining ex-employees for future hires, you may be missing out. Many companies have long considered such workers disloyal and off-limits. That started changing in the tight labour market of the late '90s, when desperation forced employers to accept ex-workers, says Beth N. Carvin, CEO of Nobscot Corp., a Kailua, Hawaii, software company that recently added a rebound recruiting module to its WebExit exit interview software.

After several years of rehiring on a limited basis, companies are having a change of heart, Carvin says. "Much to their surprise, they've found that it really does work," she says.

Other employees also become more loyal when you rehire ex-employees who left voluntarily, says John Putzier, a Prospect, Pennsylvania, HR consultant and author of Get Weird! 101 Innovative Ways to Make Your Company a Great Place to Work. "If other workers see somebody who left and came back, it makes them think maybe this isn't such a bad place after all," he says.

Rehiring can cause problems, however. If current employees see returnees awarded new titles and higher salaries, they may think they have to leave to be appreciated. And if a company is growing and changing rapidly, rehires may not fit as well as they used to.

That worried Grimmer. Questions included Gershenson's role in the now- larger organization and whether things she disliked the first time around had changed. Grimmer dealt with her questions by engaging in open, honest communication with Gershenson.

A bigger question for some companies, however, is whether to communicate at all with former employees. Open the lines by asking exiting workers if you can contact them, Carvin says, then follow up with postcards or e-mail.

Rehiring shouldn't be a blanket policy, stresses Putzier. Only go after top performers, and avoid making special offers. You can reinstate employees at their former seniority level, complete with retirement vesting, if their absence didn't extend past a year. Also, talk about a planned rehire with the employee's proposed managers to find and deal with any lingering resentment, Carvin says.

Hiring rebound employees will become more popular if the labor market tightens and indications of improved loyalty among rehires hold up long term, Carvin says. Grimmer has already made up her mind: "I maintain good relationships with a lot of people who have left. If there's a chance of them coming back, I want that door to be wide open."