Background Patient safety in hospitals is being jeopardized, as too many patients experience adverse events. Most of the adverse events arise from human factors, such as inefficient teamwork and communication failures, and the incidence of adverse events is greatest in the surgical area. Previous research has shown the effect of team training on patient safety culture and on different areas of teamwork. Limited research has investigated teamwork in surgical wards. The aim of the study was to evaluate the outcome of a team training intervention among healthcare professionals in a surgical ward after 6 and 12 months. The Systems Engineering Initiative for Patient Safety 2.0 was used as a conceptual framework for the study.Methods This study had a pre-post design with measurements at baseline, after 6 months and 12 months of intervention. The intervention was conducted in a urology and gastrointestinal surgery ward in Norway, and study site was selected based on the leaders’ willingness to participate in the project. Survey data from healthcare professionals, measured by the TeamSTEPPS Teamwork Perceptions Questionnaire, the Collaboration and Satisfaction about Care Decisions in Teams, and the unit-based sections of the Hospital Survey of Patient Safety Culture Questionnaire, were used to evaluate the intervention. A paired t-test, a Wilcoxon signed-rank test, a generalized linear mixed model and linear regression analysis were used to analyze the data.Results After six months, improvements were found in organizational outcomes in two patient safety dimensions. After 12 months improvements were found in both organizational and professional outcomes, that was in three patient safety culture dimensions and three teamwork dimensions. The generalized linear mixed model estimates demonstrated that physicians had effect on two patient safety culture measures. Furthermore, results showed that teamwork was associated with the organizational outcome Patient Safety Grade.Conclusion These results demonstrate that the team training program had an effect after 12 months of implementation. Future studies are recommended to examine the causal effect of a team training intervention in this context, preferably with studies with larger sample sizes and stronger study designs.Trial registration number:ISRCTN13997367 (retrospectively registered)