The aim of this study is to identify the prevalence of pregnancy and abortion experience, along with associated factors among street children, adolescents and youths in Porto Alegre and Rio Grande, RS, Brazil. The sampling method in this cross-sectional study was Respondent-Driven Sampling (RDS), innovative in research about hidden populations. Interviews were conducted with 307 subjects, aged 10 to 21 years. In multivariate analysis, Poisson regression with a robust error variance was used. Most of this sample were males, with no contact with school and family. Almost half of the participants had been on the street for five years or more, spending more than 15 hours per day on the streets. The prevalence of pregnancy experience was 29.3%, independently associated with being a girl, having 10 sexual partners or more in the last year, having a fixed sexual partner in the last year, and being older. The prevalence of abortion experience was 10.4%, independently associated with not living with the family, having more than two pregnancies, and being younger. The high prevalence of pregnancy and abortion experience highlights the need for the development of better sexual and reproductive health policies focused on this population.