This study aimed to measure the incidence and record the relations between risk factors of postoperative pneumonia (POP) among patients who underwent open heart surgery in a single hospital in Saudi Arabia. Methods This retrospective cohort study was conducted in June 2019 at King Abdulaziz University hospital in Saudi Arabia. Data including general information, comorbidities, lab investigations, preoperative risk factors, intraoperative considerations, and postoperative elements were collected and analyzed. Results A total of 255 cardiac surgeries were performed from November 2014 to June 2019. Two hundred of the 255 cardiac surgeries were analyzed as open-heart surgeries. Only five patients were diagnosed with POP after open heart surgery with an incidence of 2.5%. The mean age of these patients was 47±18 years, more than half of them were smokers, three were hypertensive, four were classified as ASA 4, and three underwent the operation electively. The mean bypass time was 100.3 ± 24.5 min, the mean duration of operation was 199 ± 86.2 min, the mean postoperative intensive care unit (ICU) stay was 97.4 ± 83.4 hours, and the mean overall hospital stay was 10.4 ± 7.2 days. We observed significant differences in only the following correlations: amount of blood transfusion with ICU stay and with the overall hospital stay. Conclusion The incidence of developing postoperative pneumonia in patients undergoing open heart surgery in the King Abdulaziz University hospital from November 2014 to June 2019 was 2.5%, indicating a high-quality level of surgical technique and proper infection control.