Background: The aim of this study was to identify risk factors for an adverse event, i.e. early surgical complication, need for ICU care and readmission, following ventral hernia repair. Our hypothesis was that there is an association between an increased complication rate following ventral hernia repair and specific factors, including hernia size, BMI > 35, concomitant bowel surgery, ASA-class, age, gender and method of hernia repair.Methods: Data from a hernia database with prospectively entered data on 408 patients operated for ventral hernia between 2007 and 2014 at two Swedish university hospitals were analysed. A 3-month follow-up of complications, need for intensive care and readmission, was performed by reviewing the medical records.Results: Eighty-one of 408 patients (20%) had a registered complication. Fifty-eight (14%) of these were classed as Clavien I-IIIa, and in 19 cases a Clavien IIIb-IV complication was reported. Large hernia size was associated with increased risk for early complication. A Kendall Tau test analysis revealed a proportional relationship between hernia size and modified Clavien outcome class (p < 0.001). Morbid obesity, ASA-class, method, hernia recurrence, age and concomitant bowel surgery were not statistically significant predictors of adverse events.Conclusions: Assessment of hernia aperture size is of great importance in the preoperative evaluation of ventral hernia patients to consider risk for post-operative complications. These results suggest a careful attitude when applying watchful waiting concepts and when postponing hernia surgery to achieve weight loss. A delaying attitude may result in increased risk of complications caused by increasing hernia size. [ABSTRACT FROM AUTHOR]