BY OSCAR CORRAL

There was a time, Adriana Bosch said, when she didn't think Fidel Castro was so evil.

She lived in Boston in the 1970s, and the infectious rhetoric of leftists and hippies had gotten to her. Far removed from the anti-Castro fervor of exile Miami and New Jersey, there were few around to shake some sense into her, she said.

''It was fashionable,'' she said of her Castro ambivalence.

Today, Bosch calls herself a neo-conservative, and her opus on Fidel Castro, a two-hour documentary by that name to air nationally on PBS Monday, should settle the question of how she feels about him. At least she hopes so.

''I'm not supposed to vent my feelings,'' she said, when explaining how she wanted to portray Fidel in her film. ``I'm supposed to look at facts, draw as objective a portrait as I can. Fidel is a man driven by his own ambition. But to think that's all there is to him is underestimating him.''

Bosch, who left Cuba in 1968 at age 13, did not try to put her feelings about Castro aside, but instead ''went head-on into them,'' she said.

During an interview at the Biltmore Hotel, Bosch cradled a pink Campari and soda. She wore a pink shirt with a pink sweater draped over her shoulders, a tropical update to the gray Boston image she embraced for two decades.

GRUDGING RESPECT

She harbors a certain respect for Castro. ''He has goals, he has ambition, a definite sense of where he thinks he is going,'' she said. ``You don't have the kind of purges under him that you saw under Stalinism.''

However, Bosch says she harbors no illusions about Fidel. She points out his abysmal record on human rights, including his role in summary executions, and believes Castro is interested first and foremost in maintaining power.

''This is not a defense of Fidel Castro,'' she said. ``I really want people to see it and think for themselves.''

The documentary is the latest in a string produced by Bosch for PBS' highly regarded American Experience that includes portraits of Ronald Reagan and Jimmy Carter.

Bosch, 49, said she did not want the film to be viewed as an ''exile piece.'' So she chose a white non-Hispanic actor to narrate it. Her idea was to make the documentary interesting to all Americans, not just Cuban exiles.

Miami has been abuzz about the movie the last few days.

''The documentary is extraordinary,'' said local talk show host Maria Elvira Salazar, who saw the film. ``It's the first time that through images and by telling the story in an impartial way, the audience sees what a high social cost the Cuban people have had to pay for the megalomania of Fidel Castro.''

Bosch wants to make a couple of things clear. She is not related to Orlando Bosch, the exile figure who was accused of bombing an airliner that killed dozens.

Nor does she belong to the Bosch family that are heirs to the Bacardi fortune.

MET CASTRO AT AGE 4

She was born in Santiago de Cuba in 1955, and had her first and only meeting with Castro when she was 4. Castro had returned to Santiago in 1959 for the first time since he took over Havana, and Bosch's father, a cattle trader, had taken her to the airport to greet him.

The young revolutionary picked up Bosch and gave her a kiss. ''Que gordita mas bonita,'' (what a pretty little fat girl) she remembers him saying.

Her family fled to Spain in 1968, and later to Elizabeth, N.J., where her father became a butcher and her mother took a job in an organ factory.

After graduating from Rutgers University with a degree in political science and Spanish literature, she moved to Boston in 1977 to obtain a doctoral degree from the Fletcher School of Law and Diplomacy, run jointly by Harvard and Tufts universities.

Surrounded by ''hippie and leftist types,'' Bosch began to think maybe Castro wasn't so bad.

Her view changed when she did a dissertation on Nicaragua's Sandinista movement and its negative impact on society. While working on a documentary on Central America, she fell in love with television and filmmaking. She moved to Miami from Boston last summer.

Although she did not interview Castro, Bosch amassed a collection of archived footage.

''It presents a very objective image of Fidel,'' said journalist Carlos Alberto Montaner, who saw the film. ``The final result is very negative for his [Castro's] image.''

As for Bosch's predictions about the future of Cuba, she said that Castro's biggest mistake is that he personifies his revolution, so once he dies, it may die with him.

''Castro is looking for a history that will absolve him, acquit him, but he hasn't found it,'' she said.