To assess the impact of implementation of the TeamSTEPPS teamwork improvement concept on patient safety culture.Pre-post culture assessment using the Hospital Survey on Patient Safety Culture, at baseline and one year after implementation of TeamSTEPPS.Two maternity wards within the same 480-bed multisite teaching hospital.Implementation of the TeamSTEPPS teamwork improvement concept.Analysis of variation of the percentage of positive responses (score) in both wards (intervention and control) was conducted.There was a significant increase in scores in three dimensions of patient safety culture in the intervention ward: Supervisor/Manager Expectations and Actions Promoting Safety increased from 48.7% in 2015 to 70.8% in 2016 (P < 0.005); Teamwork Within Units increased from 35.5% in 2015 to 54.5% in 2016 (P < 0.005); Nonpunitive Response to Errors increased from 16.7% in 2015 to 32.3% in 2016 (P < 0.005). Other dimensions showed no significant changes. In the control ward, there was a significant decrease in scores in one dimension. A secondary analysis of differences in differences still shows significant improvement in one dimension (Supervisor/Manager Expectations and Actions Promoting Safety P < 0.005).After implementing the TeamSTEPPS teamwork concept, patient safety culture significantly improved for three of twelve dimensions in the intervention group. When controlling for differences in baseline scores between implementation and control wards, a significant improvement remains in one dimension. This suggests that TeamSTEPPS could be considered when seeking to enhance patient safety culture, especially in high-risk environments such as maternity wards.