Objectives To understand the changes on sexual and contraceptive behaviours of unmarried induced abortion(IA) youth by intervention in Sichuan, China; and to find a way to improve sexual and contraceptive behaviours of unmarried IA youth. Methods Intervention epidemiological surveys (baseline and evaluation) plus qualitative interview were used. During July 2002 and July 2003, 2 484 unmarried female volunteers who aged 15-29 years and come to clinics seeking abortion were recruited by cluster random sampling from the four selected regions of Sichuan, 48 volunteers were interviewed for 8 focusgroup discussions (FGDs) and 16 in-depth interviews equally for each survey. Information, education anol communication(IEC) materials, education sessions, trainings and counseling were given to subjects and service providers during the project implementation. Questionnaires for surveys and guidelines for qualitative interviews were used.Results Comparison of the after with the before intervention: 1) the proportion of respondents having knowledge about sexuality was increased by 13％. Among them,the proportion of respondents got part and most of the knowledge was increased by 43％. Maximum number of sex partners the respondents have decreased from 9 to 4. Respondents' partnerships have gradually changed from more acquaintances/school mates/boy friends to fiancés mainly; 2) respondents' contraceptive use rate was in creased by 20%. Among them, the condom use rate increased rapidly to 80%.Purposes of condom use were changed from only for contraception to for prevention of HIV/AIDS/STDs and pregnancy. And most of respondents stabilised their method use - condoms. Most of respondents suggested condoms was the method most suitable for unmarried IA youth, this proportion was increased by 44%; 3) proportion of respon dents knowing more about consequences of induced abortion was increased by 24%; and 4) proportions of respondents having depression and anxiety symptoms were decreased by 66% and by 61%, respectively.Conclusion The intervention including IEC materials, education, training and counseling was effective in improving sexual and contraceptive behaviours of unmarried IA youth.