The jurors, in Superior Court in Atlantic City, found that Vioxx did not contribute to the heart attack that the woman, Elaine Doherty, suffered in 2004. They also ruled that Merck had warned Ms. Doherty’s doctor of the drug’s risk and did not defraud consumers. The company lost one part of the ruling when jurors held that Merck did not warn Ms. Doherty herself about the drug.

Merck has won two earlier trials, with a split verdict in a third. It has lost three Vioxx cases, with verdicts totaling $298 million — damages that will be reduced to $48 million because of limits on state punitive awards. The company potentially faces more than 10,000 lawsuits related to Vioxx. It has allocated almost $1 billion to defend itself, pledging to fight each case.

“This really reinforces our strategy of trying every case,” said James C. Fitzpatrick of the law firm of Hughes Hubbard & Reed, who represented Merck. “We made the appropriate safety disclosures to doctors, and we demonstrated that Vioxx did not cause Mrs. Doherty’s heart attack.”

Some analysts said that Merck would eventually have to reach a global settlement. The verdict yesterday will help any such effort, said Stephen G. Brozak, an analyst with WBB Securities. “The thing shareholders fear the most is there is no settlement that is financially suitable for Merck,” he said. “Every time they are able to win in court, that settlement price goes down.”

Merck withdrew Vioxx in September 2004 after a study showed it doubled the risk of heart attacks in people taking it for 18 months. The company attributed Ms. Doherty’s heart attack to her age, weight, diabetes, cholesterol, blood pressure and clogged arteries. Ms. Doherty, who is 5 feet 3 inches, once weighed 265 pounds and has long been a diabetic.

A juror, Joseph Calabrese, told reporters, “We simply believed that the risk factors were too insurmountable.” The jury decided the case in its second day of deliberations.

Ms. Doherty’s lawyers said she was controlling her risk factors when she had a heart attack at home in Lawrenceville, N.J., in January 2004. She had lost nearly 100 pounds, her blood pressure was normal, and her diabetes and cholesterol level were improving, a lawyer, James J. Pettit, said in closing arguments. Another plaintiff’s lawyer, Gene Locks, hailed the jury’s 7-to-0 vote that Merck failed to warn her of the drug’s risks. Past juries have considered only whether Merck warned doctors.