The youth are among the vulnerable population for contracting Human Immune deficiency Virus (HIV) and Acquired Immuno deficiency Syndrome (AIDS), which are behavioural related problems. This paper examines sexual behaviour risks for HIV and AIDS infection among youth. A total of 232 youth both in and out of school aged 15-35 years were involved in the study. A cross sectional study design was adopted and data was collected through questionnaire, Non participant observation and documentary review. The study used descriptive statistics to determine frequency, percentages and the mean scores for sexual behaviour risks among the youth in the study areas. The findings showed that more than a half of the sexually active youth had had sexual intercourse and among the youth who had already had sexual intercourse, a half of them did not use condoms. The results showed significant differences in sexual behaviour risks among youth in the study areas (p < 0.05). Youth in Mufindi were at a higher risk than was the case with their counterparts in Mbulu. The study call for creation of youth programmes that will focus on reduction of sexual behaviour risks among the youth. Programmes for youth can focus on a range of services including prevention strategies, risk reduction, and behaviour change. Keywords: Youth, Sexual behaviour risks, HIV and AIDS, Infection, prevention, Tanzania DOI: 10.7176/DCS/9-5-06 Publication date:May 31st 201