The study found that 27 percent of a sample of 2,880 children and youth ages 10-16 who identified themselves as Internet users had been exposed to Internet messages with sexual content, mostly involving images of human nudity and sexual activity. Boys were more likely than girls to receive these message, usually in unsolicited e-mails from unknown sources or from friends. Exposure to Internet sexual content increased with age; 20 percent of the recipients were young, 27 percent medium-age, and 43 percent older children and youth. Seventy-eight percent of the sample used chat rooms on the Internet; 28 percent of these chat-room users were asked intimate details during chat sessions, with girls reporting significantly more exposure to such questions than boys. These questions involved direct requests for sexual activities and conversations outside the chat room on the phone or in person. Nearly one-half of the boys and one-third of the girls exposed to messages with sexual content did not confide to anyone about their experience. Thirty-two percent of boys and 47 percent of girls confided their experience to friends; 15 percent of boys and 25 percent of girls told their parents about the messages. The most reported behavioral reaction to receiving such messages was to open the message, read it, and delete it. Girls deleted the messages more often than boys. One-fourth of the children had a disturbing emotional reaction. After being asked about intimate details during a chat session, 27 percent of the participants reported feelings of trepidation, shame, and fear. These feelings were most often experienced by girls and younger children. 3 tables and 8 references