To determine the incidence rate and risk factors associated with the development of diaphragm hernias following left diaphragm procedures at the time of ovarian cancer cytoreduction. We retrospectively reviewed data from patients diagnosed with epithelial ovarian, fallopian tube, or primary peritoneal carcinoma who underwent any timeframe of cytoreductive surgery (primary, interval, secondary, tertiary) at our institution from December 2010 to September 2024. Patients were included if they underwent left diaphragm peritonectomy or resection as part of their cytoreductive surgery. The diagnosis of left diaphragm hernia was made by computed tomography of the chest either as an incidental finding during follow-up surveillance or during work-up for symptomatology. We utilized statistical analysis with descriptive proportions with interquartile ranges. A total of 267 patients with ovarian cancer underwent a left diaphragm peritonectomy or resection as part of their cytoreductive surgery at our institution and were included in the study. The overall median age was 62 years (interquartile range; 52-70) and body mass index 24.9 kg/m Diaphragmatic hernias occurred most often following the setting of concurrent splenectomy; however, splenectomy was not a statistically significant risk factor. These findings provide meaningful insight into the frequency and clinical context in which this complication may arise, addressing a critical knowledge gap in the surgical management of patients with ovarian cancer who require upper abdominal and thoracic procedures.