PIP: 3101 women aged 20-44 were surveyed in Flanders in 1982-83 concerning their perceptions of the contraceptive methods they used. The survey was part of a larger longitudinal study of changes in family formation in Belgium. Traditional and modern contraceptive methods were perceived very differently. Withdrawal/periodic abstinence and the condom were regarded as effective by 61% and 79% of respondents, while the IUD, pill, and female sterilization were believed by 99% of respondents to be effective. Traditional and intermediate contraceptive methods were believed to be less convenient to use, to be more frustrating sexually, but to be more natural. The IUD and pills were associated with higher risks of secondary effects, but oral contraceptive (OC) users believed their method to be much more harmful to their health than did IUD users. IUD users complained of physical secondary effects, while OC users complained of physical, psychic, and sexual secondary effects. Fewer IUD users than OC users believed their method to be highly effective. Considerable proportions of withdrawal, periodic abstinence, and condom users appeared to overestimate the efficacy of their method. Sterilization users believed the accessibility of their method to be significantly lower than did users of other methods, perhaps because sterilization has become accepted and widely available in Flanders only in the past few years. The most frequently cited advantages of withdrawal/periodic abstinence and the condom were naturalness, innocuity, and lack of secondary effects, while the most frequently cited advantage of OCs and sterilization was their efficacy. Ease of use and efficacy were both cited as advantages by IUD users. A large number of women, especially those using modern methods, stated their method had no major disadvantages. The principle disadvantages cited by withdrawal, abstinence, and condom users were low efficacy and inconvenience for sex life, while the principle disadvantages for the pill and IUD were health worries and secondary effects. Perception of the attributes of the contraceptive method used was influenced more by prior contraceptive use than by age, educational level, ideology or completeness of the family. As in other countries, users of modern methods seem to be more satisfied with their choice. Reasons for terminating use of different methods used in the past were directly related to their perceived disadvantages. Secondary effects and health worries were the major reasons for terminating OC and IUD use. A nonnegligible proportion who terminated IUD use cited its lack of efficacy.