Unwelcoming behaviours and judgemental attitudes have long been recognised as a barrier to young people's access to reproductive health services. Over the last decade youth friendly reproductive health services have been promoted and implemented world-wide. However, long term evidence of the impact of these programmes is lacking. We report the results of a large mystery client evaluation of adolescent sexual and reproductive health services in Tanzania, a country that has had a long established youth friendly policy. Forty-eight visits made to thirty-three health facilities were conducted by twelve young people (six in each region) trained to perform three different scripted scenarios (i.e., condom request, information on sexually transmitted infections and family planning). The study revealed barriers in relation to poor signage and reception for services. In addition health workers demonstrated paternalistic attitudes as well as lack of knowledge about adolescent sexual and reproductive health services. In some cases, health workers discouraged young people from using services such as condoms and family planning methods. Lack of confidentiality and privacy were also noted to be common challenges for the young people involved. Intervention strategies that focus on changing health workers' mind-set in relation to adolescent sexual and reproductive health are crucial for ensuring quality provision of sexual and reproductive health services to young people. The study identified the importance of reception or signs at the health units, as this can facilitate young people's efforts in seeking sexual and reproductive health services. Likewise, improvement of health workers knowledge of existing policy and practice on sexual and reproductive health services and youth friendly services is much needed.