Abstract Body (Do not enter title and authors here): Background: Physical activity (PA) has been shown to improve cardiovascular outcomes, including health-related quality of life (HRQoL), in patients with acute coronary syndromes (ACS). Furthermore, studies have shown the impact of perceived social support (PSS) in enhancing PA levels and, as a result, improving important outcomes such as HRQoL in patients with ACS. Despite numerous studies focusing on PA, PSS, and HRQoL in cardiac patients, these variables remain to be examined in Saudi patients with ACS. Research Question: Is there an association among PA, PSS, and HRQoL in patients with ACS in Saudi Arabia? Methods: Patients with ACS hospitalized at King Abdulaziz Medical City, Riyadh, Saudi Arabia, were enrolled in this cross-sectional study. The EuroQoL (EQ-5D-5L), Global Physical Activity Questionnaire, and Multidimensional Scale of Perceived Social Support were used to measure HRQoL, PA, and PSS, respectively. Results: The sample consisted of 208 Saudi patients with ACS. The sample had a mean age of 59 years [standard deviation (SD) =11.94] and was predominantly male (77.40%); over half the sample had not completed high school (62.50%). Among the study participants, 44.23% were married, and 44.23% were retired. The sample reported a high PSS average of 68.40 [SD=11.94] as well as a high mean HRQoL of 7.52 [SD=2.78]. However, compared to the WHO recommendation for PA, 94.23% of the sample reported low PA levels. A multiple linear regression model showed that neither PSS (P = 0.52) nor HRQoL (P = 0.50) was significantly associated with PA levels. At the same time, PSS was significantly positively associated with HRQoL (P = 0.04), even after adjusting for age, gender, education, and job status. Conclusions: While a significant positive association was found between PSS and HRQoL, PA was not significantly associated with either of these study variables. This result may be due to lack of variation in PA levels within the sample as well as recall and social desirability biases. Further studies of larger samples in addition to use of device-assisted measures could help to overcome these limitations.