For years, drug manufacturers have treated physicians to free trips and expensive dinners as an insidious way of promoting their patented medications. Turns out, they have been seducing Defense Department officials in much the same way.

An investigation by the nonprofit Center for Public Integrity has revealed that the health-care industry paid for 40 percent of all free trips taken by Pentagon officials in the past decade.

Johnson & Johnson paid for 187 trips by Pentagon personnel, at a cost of more than $215,000. GlaxoSmithKline, formerly headquartered here, underwrote 95 trips at a cost of more than $120,000. All told, drug companies and medical-device firms spent about $10 million on more than 8,700 trips for Defense Department doctors, medical researchers, pharmacists, and others. Why? Because the military spends a lot of your tax money on prescription drugs.

The Pentagon's budget for prescription medications tripled from fiscal year 2000 to 2006, to $6.2 billion. Defense spending on medications accounts for about 2 percent of all drug sales nationally.

Drug companies told the authors of the CPI's report that they follow the law and government regulations carefully in paying for such trips. But the too-cozy nature of these arrangements was acknowledged earlier this year when the Pentagon's head of pharmaceutical operations prohibited his immediate staff from going on company-paid trips.

Studies have shown that doctors who receive drug company perks were more likely to prescribe that company's medication. The American Medical Association discourages physicians from accepting such freebies.

The law should be changed to disallow Pentagon officials from accepting these perks. The current system is brimming with potential conflicts of interest.

The health-care industry isn't alone in offering free trips for the Defense Department. The CPI's yearlong investigation found that outside sources paid for more than 22,000 trips for military officials in the past decade, at a cost of more than $26 million. Thousands of trips included popular vacation spots such as San Diego, Las Vegas, Honolulu, and Venice, Italy. Spouses often went, too.

Sony, Nike, and toy-maker Mattel paid for more than 500 trips. These companies are interested in making sure their products are sold at the retail exchanges and other stores on military bases.

The Pentagon's $500 billion annual budget should be enough for personnel to take the trips necessary to carry out their jobs. Potential conflicts abound when outside firms seeking business pay for trips. Congress needs to prevent these practices from occurring.