In the Open Dialogue (OD) based psychiatric services adolescent patients receive less medication and are more often treated within an outpatient setting as compared to standard services. An evaluation of the possible risks of implementing OD are required. The aim of this longitudinal register-based study was to evaluate how treatment under OD is associated with the probability of suicide as compared standard psychiatric care. Study included all 13- to 20-year-old adolescents who enrolled to a psychiatric service in Finland in 2003–2013. The OD-group included adolescents whose treatment commenced in the Western Lapland area (n = 2107), this being the only region where OD covered all psychiatric services. The comparison group (CG) included rest of Finland (n = 121,658). Information was gathered from onset of treatment to the end of the 5-year follow-up or death. In a multivariate Cox regression there were no statistically significant differences in 5-year suicide hazard ratios between OD and CG.