It depends on the nature of the insurance. You can deduct the premiums if the policy pays or reimburses your actual medical expenses. But you cannot deduct premiums for "Policies that pay you a guaranteed amount each week for a stated number of weeks if you are hospitalized for sickness or injury" (quote from IRS Publication 502). Also, if the policy pays for anything other than medical care, you can only deduct the portion of the premiums that is for medical care. The insurance company has to tell you how much of the premium is for medical care.
In addition, you can only deduct medical insurance premiums that you pay with after-tax money. You cannot deduct premiums that are paid by a pre-tax deduction from your pay.
