Whether it's merely a lingering smooch or a seismic roll in the sheets, romance on the big screen looks effortlessly erotic, a fusion of souls and flesh that raises pulse rates in theaters, video dens and studio counting rooms. But making great love scenes is more difficult than making great love. Stars of both sexes would rather work with poisonous reptiles than clinch on-camera. "You sit and sweat in your trailer," says Meg (The Doors) Ryan. "Everyone is tense, and you comfort yourself with strange little thoughts like, 'I get to have underwear on!' "

No wonder actors go off the deep end. They have to simulate the most intimate of human relations with a partner they barely know in a soundstage full of people. According to Demi Moore, she and sensitive specter Patrick Swayze, at the pottery wheel in Ghost, "felt like we were in high school on a first date. And here we had to act like we had known each other and were comfortable with each other. We were all arms. His face was so beet red! I would say, 'Please don't let my breast be exposed.' And he would say, 'Okay.' If he noticed my shirt coming up over my rear, he would pull it down. We finally just said, 'I'm really nervous and I hate this.' Then it was okay."

Actors don't drop drawers at the drop of a hat, says Big Easy director Jim McBride. "You have to find some character motivation so it's not just, 'Okay, take your clothes off and roll around on the bed.' " While directors coddle and protect their love-scene principals, they sometimes defuse tension with humor. Julia Roberts was accomplished and confident beyond her 23 years, but she had little experience with sex scenes before Pretty Woman. She was uncomfortable at being scantily clad, so when she submerged during the first take of the film's bubble-bath scene, director Garry Marshall waved everyone off the set. She surfaced to find an empty room. "She was startled," says Marshall. "Then she laughed and got the idea that we were going to do this lightly."

Despite actors' insistence that lovemaking on the set is all in a tense day's work, don't they ever get excited? "Absolutely," says Fatal Attraction director Adrian Lyne. "Otherwise, something's missing. I felt there was real heat between Glenn [Close] and Michael [Douglas], and it showed." According to Swayze, body English is beside the point. "It's what the audience reads in your eyes. If the passion isn't there, it just looks like two people sucking face."