MONTPELIER, Vt. (AP) _ The Vermont Supreme Court has ruled that parents may sue to recover damages for loss of companionship when an adult child is killed.

In a unanimous decision setting Vermont apart from most other states, the five-member court said, ''Children have an intrinsic value to their parents, regardless of who was supporting whom at the time of death.''

The ruling was based on a lawsuit by the parents of an 18-year-old college student killed by a drunken driver in September 1985.

Jane emily Clymer, a University of Vermont junior, was walking her bicycle along a road near Burlington when she was struck and fatally injured by a car.

The driver, Theron Webster, was sentenced to three years in prison for drunken driving with death resulting. Webster has served that sentence.

The victim's parents reached a $120,000 settlement with Webster's insurance company, and sued two South Burlington bars, Wesson's Diner and The Rotisserie, where Webster had been drinking before the accident.

A judge had ruled that Clymer's parents could not sue for loss of companionship because their daughter was 18 when she died. But the state Supreme Court on Friday reversed the decision, and ordered a trial.

''Whether the dependent child is an adult or a minor, society recognizes the destruction of the parents' investment in affection, guidance, security and love,'' the court said.

The victim's father, Adam Clymer, The New York Times' chief congressional correspondent, said the decision acknowledges ''there isn't something mechanical that occurs on an 18th birthday that diminishes the love between parents and their children.''

The Clymers' lawyer, William Gray, said a second aspect of the decision is significant for Vermont law. He said the law covering liability for tavern owners and bartenders had previously been interpreted to shield them from punitive damages.

Gray said the Supreme Court ruled punitive damages could be collected if the plaintiffs could show that the bartenders' in serving an apparently drunken patron was ''wanton and reckless and not just plain negligent.''