Résumé : Accreditation is an internationally recognized evaluation process used to assess, promote and guarantee efficient and effective quality of patient care and patient safety. This study provides valuable information as to the impact of accreditation in a unique multicultural, multi-language competitive environment at King Abdul-Aziz University Hospital in Saudi Arabia. To achieve an unbiased assessment of the impact of accreditation on quality of patient care and patient safety as perceived by nursing staff. A cross-sectional surveys were conducted pre and post accreditation. A total of 870 registered nurses of 8 different cultural backgrounds from 22 hospital units participated in an electronic accessed surveys. A five point Likert scale was used. For comparison, the pre and post-survey results were statistically analyzed using the McNemar test for testing the significance. A total of 721 nurses answered the survey questionnaire, 675 met the survey criteria. The comparison of percentages of those who answered Agree and Strongly agree pre and post-accreditation items showed post-accreditation improved perception on the quality of patient care and patient safety and promoted good safety practices. Accreditation has an overall statistically highly significant perceived improvement on quality of patient care and patient safety (p<0.001). © Medwell Journals, 2011.