ATLANTIC CITY, Nov. 3 - The drug giant Merck won decisively Thursday in the second Vioxx-related personal injury case to go to trial, an outcome that legal experts say could slow the flood of lawsuits against the company.

A nine-member jury in a state court here found by an 8-to-1 vote that the painkiller Vioxx had not caused Frederick Humeston, a 60-year-old Idaho postal worker, to have a heart attack in September 2001. Mr. Humeston, who survived, testified in the case.

Perhaps just as significant for Merck, which is already the subject of thousands of Vioxx cases and in August lost the first one to go to trial, the jury concluded unanimously that the company had properly marketed the drug. Vioxx was taken by 20 million Americans between 1999 and 2004. Merck stopped selling it after a clinical trial linked the drug to heart attacks and strokes in patients taking Vioxx for 18 months or longer.

The case was heard in Atlantic County Superior Court before Judge Carol E. Higbee, who is overseeing more than 2,900 suits filed in state court in New Jersey against Merck, which is based in Whitehouse Station, N.J. In all, more than 6,400 lawsuits have been filed against Merck in state and federal courts, and tens of thousands more are expected.

At a news conference after the verdict, Vickie Heintz, a juror, said that lawyers for Merck had convinced her that Mr. Humeston's heart attack had probably resulted from stress and anxiety, not from Vioxx. Mr. Humeston took Vioxx for less than two months before his heart attack.

"I just think Mr. Humeston had way too many health issues to pinpoint it to Vioxx," Ms. Heintz said. "Stress was a huge factor in my decision." The jury deliberations, which lasted for nine hours over three days, were largely free of rancor, Ms. Heintz said.

Lawyers for Merck said they were pleased that the jury had decided that Merck did not conceal Vioxx's risks from doctors or consumers, even though company documents and e-mail messages show that Merck scientists were concerned about Vioxx's potential heart dangers as early as 1997.

"The company did provide information fully and promptly to the regulatory and scientific community," Kenneth C. Frazier, Merck's senior vice president and general counsel, said in a conference call with reporters after the verdict.

Merck and federal regulators continue to discuss the possibility of returning Vioxx to the market, Mr. Frazier said. Merck's shares rose $1.07, or 3.7 percent, after the verdict, closing Thursday afternoon at $29.48.

Merck's lawyers hugged and kissed after Judge Higbee read the verdict in the Atlantic County Superior Courthouse just before 11 a.m. Two members of the Merck trial team began to cry.

The decision comes less than three months after a Texas jury found Merck liable in the first Vioxx case to reach trial and awarded the plaintiff - the widow of a man who took the drug - $253 million, a decision that caused Merck stock to fall 8 percent that day. Texas law limits that award to $26 million, and Merck has vowed to appeal the case.

"We do have a good story to tell, and we are fully committed to telling it," Mr. Frazier said.

Merck this time also benefited from an evidently less sympathetic plaintiff, compared with the grieving widow in Texas. Letters that Merck lawyers showed to the jury indicated that Mr. Humeston often complained to his United States Postal Service supervisors about his workload. And the jury was told that the Postal Service was investigating Mr. Humeston as a suspected malingerer.

Christopher Seeger, Mr. Humeston's lawyer, sometimes seemed to struggle to connect with the jury. Ms. Heintz, one of only two jurors to speak to reporters after the verdict, said that Mr. Seeger and the other lawyers for Mr. Humeston "were like barracudas."

Mr. Seeger said afterward that the verdict was unfair and wrong but acknowledged that he shared responsibility for the loss.

"I'm going to be second-guessing myself for the way I tried this for many months," Mr. Seeger said afterward. "Obviously, the jury rejected Humeston."