(MONEY Magazine) – If you've been told that you can't get insurance--you've had a bypass operation, perhaps, or have diabetes--don't take no for an answer. First check any policy you have for a "guaranteed insurability rider," which gives you the right to buy more coverage at your current rate. Then look into group insurance (which usually doesn't require a medical exam). If neither option applies, you may be a candidate for "impaired risk" insurance. Although some insurers still use mortality tables based on data from the 1970s, others now rely on clinical medical underwriting, which considers medical advances and lifestyle choices that allow people with health problems to live long lives. To find impaired risk coverage:

--Call a company that specializes in high-risk policies. Among them: CNA (800-437-8854); U.S. Financial (513-287-6820); Midland (800-253-7113); United of Omaha (402-342-7600); and Guarantee Trust Life Insurance (800-338-7452; particularly for people with HIV).

--Contact Impaired Risk Specialists (800-285-3279) or Underwriting Specialists (800-652-5700), which locate impaired-risk policies.

--Check lists of independent and company-affiliated agents who specialize in impaired risk in Who Writes What, published by the National Underwriter (800-543-0874; $10).

--Choose an agent who has experience with high-risk policies and can shop your case to various companies. Norman Barken, a Los Angeles underwriter who has been handling impaired-risk clients for 40 years, says many agents are not aware of impaired-risk policies or are contractually bound to companies that don't write them. You may want to work with two agents to see which one offers a better deal. But don't expect to dicker about the quotes you get; they're based on contracts with underwriters and are likely to be firm.

--VANESSA RICHARDSON