Introduction Sexually transmitted infections and HIV among adolescents in India, has emerged as a separate epidemic in the recent years. STIs elevate the vulnerability of young people to HIV. The present study aimed to evaluate knowledge and awareness of STI-HIV and its prevalence among adolescents in India.

Methods A sample of 20 808 unmarried adolescents (15–19 years) from Youth in India: Situation and Needs Study (2006–07) was analysed. Bi-variate and multivariate techniques were applied to accomplish the objective.

Results Although 80% of the adolescents knew about HIV/AIDS, only 11% had heard about STIs. Only half of the respondents had comprehensive knowledge on the two ways of HIV prevention (condom use and single partner relation). While boys were more aware about STIs and HIV/AIDS, girls lagged behind in having accurate information. Nearly one third of the adolescents had common misconceptions about HIV transmission. STI-HIV awareness was more among adolescents with higher education, living in urban areas, belonging to rich families and those who received sex education. Around 10% of the adolescents - 4% boys and 12% girls, reported symptoms of STI in past 3 months. STIs were more prevalent among illiterates, living in rural areas, belonging to poor and middle class families and who received sex education from proper source like family, media and NGO/health workers. Logistic regression revealed that adolescent girls (p<0.001) and respondents from rural areas (p<0.01) were significantly more likely to report STI symptoms. Respondents who received sex and family life education from reliable sources were more likely to report STI problems. Adolescents belonging to upper wealth quintile were 24% less likely (p<0.01) and who had high awareness of STI-HIV were 12%–15% less likely to report any symptom (p<0.10).

Conclusion Findings underscore limited awareness about STIs, HIV prevention and transmission specifically among adolescent girls. There is an immense need to implement gender-based sex education in schools and social campaigning to increase awareness.