Background: Patient safety is one of the main components of good-quality health services. The main objective of this study is to explore the most effective factors relating to patient safety in Iran.

Methods: This qualitative study was done using content analysis. Data were collected using semi-structured interviews. Through purposive sampling, 14 participants were selected by experts who were familiar with the patient safety friendly hospital program. Interviews were recorded and then analyzed by framework analysis using MAXQDA software.

Results: Of 2,474 initial codes, 10 main themes and 53 sub-themes were identified, including importance of human resources; organization and management; interactions and teamwork; medication; equipment and physical environment; patient-related factors; patient safety and quality improvement; the importance of documentation; assessment and monitoring; medical errors; barriers and challenges.

Conclusion: Factors affecting patient safety can be divided into two groups: facilitators and barriers. Hospitals can improve the implementation of patient safety standards, reduce the adverse events and enhance patient safety by strengthening facilitating factors, such as providing human resources, adequate medical equipment and facilities, increasing employee participation in quality improvement programs, improving staff training, communicating with patients and their families, and addressing the existing challenges and barriers.