FORTUNE — Dear Annie: Why do so many companies request personal references on job applications (especially online) even before setting up an interview? They usually ask for contact information for teachers, relatives, and acquaintances, as well as bosses and coworkers, both current and former.

I’m really not comfortable with this, for several reasons. First, I’m in my mid-40s and have been out of college a long time, so giving professors as references isn’t practical. Second, I don’t like to provide information on family and friends because it’s too personal. As for work-related references, most of my previous colleagues and supervisors have retired or moved on, and I’ve lost touch with them. And I don’t want anyone at my current company to know I’m job hunting, so they’re out too. So my question is, can I just decline to give references? Employers usually don’t take the time to check them anyway, do they? — Stumped in San Francisco

Dear Stumped: Well, of course you can decline to give references — but don’t be surprised if that brings any further contact with a prospective employer to a screeching halt. “Companies certainly do check references,” says Jeff Shane, executive vice president of reference-checking firm Allison & Taylor. “Especially in this job market, where there are often many qualified candidates competing for each opening, saying ‘no’ to this request is rolling the dice.”

Personal references are relatively unimportant, he adds, since kind words from your friends “generally don’t carry much weight anyway. What is critical, however, is strong professional recommendations, particularly from former bosses.” Refusing to let hiring managers contact them, Shane says, is “a red flag” — in large part because it suggests you have something to hide — and could well cost you the job before you’ve even been interviewed for it.

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So what should you do now? First, try to track down at least two or three of the people who were familiar with your work in the past and with whom you’ve since lost touch. Ideally, these would be people to whom you reported, but erstwhile peers and others (satisfied clients, for example) will do in a pinch. Google them, look them up on LinkedIn, or see if professional associations or mutual acquaintances have any information on how to reach them.

It’s nice of you not to want to bother former bosses who have retired, but if you thank them profusely for understanding the importance of your request, you’ll probably find your misgivings are misplaced. Managers who have done any hiring at all are well aware of how much references matter, so they’re unlikely to resent your asking. If you want to keep your intrusion on their time to a minimum, you can always write your own letter of recommendation and ask them to sign it.

All this detective work and diplomacy is worth the effort, says Shane, because “if an employer is really interested in you and you don’t provide references, they may go to Plan B.” That’s where the hiring manager or a human resources person calls the HR department at a company where you used to work and fishes around for someone who remembers you and who is willing to chat about what your work was like.

The trouble with that, of course, is that the person they stumble across could turn out to be an old nemesis who (even if company policy officially forbids it) will be only too happy to trash you — and then you’ll really wish you had taken the time to locate a few of your fans.

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In this as in so much else, a bit of advance planning can avert a huge hassle later on. “The trick is not to lose touch with potential references in the first place,” says Shane.

When you leave a job where you’ve worked well with your boss, or if a boss who likes your work is moving on, make it a point to hold on to his or her contact information. Then call or email every now and then, just to say hello and stay current with what he or she is up to lately.

“Send a card at the holidays, maybe even meet for coffee once in a while,” Shane suggests. “This way, when there is a specific job you want, and you’d like to give this person as a reference, you can coach them a little bit on what you’d like them to say to a prospective employer, because you’re not calling out of a clear blue sky.”

Keeping in touch is smart for one other reason: Since former bosses often have a way of moving onward and upward to bigger and better things, they sometimes turn out to be future bosses, too.

Talkback: Do you find it difficult to give references when employers ask? Have you ever been unpleasantly surprised by what a reference said about you? Leave a comment below.


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