The purpose of this paper is to assess the association between shift schedule realignment and patient safety culture. Using difference in differences model, BIMC Hospitals and Siloam Hospital Bali were compared before and after shift schedule realignment to test the association between shift schedule realignment and patient safety culture. Shift schedule realignment was associated with a significant improvement in staffing (coefficient 1.272; 95% CI 0.842 - 1.702; p<0.001), teamwork within units (coefficient 1.689; 95% CI 1.206 - 2.171; p<0.001), teamwork across units (coefficient 1.862; 95% CI 1.415 - 2.308; p<0.001), handoffs and transitions (coefficient 0.999; 95% CI 0.616 - 1.382; p<0.001), frequency of error reported (coefficient 1.037; 95% CI 0.581 - 1.493; p<0.001), feedback and communication about error (coefficient 1.412; 95% CI 0.982 - 1.841; p<0.001) and communication openness (coefficient 1.393; 95% CI 0.968 - 1.818; p<0.001). With positive impact on patient safety culture, shift schedule realignment should be considered as quality improvement initiative. It stretches the compressed workload suffered by staff while maintaining 40 h per week in accordance with applicable laws and regulations. Shift schedule realignment, designed to improve patient safety culture, has never been implemented in any Indonesian private hospital. Other hospital managers might also appreciate knowing about the shift schedule realignment to improve the patient safety culture.