Background: Obesity surgery is increasingly and successfully applied in the treatment of morbid obesity. Nevertheless, long-term side effects are common and may affect patients’ eating behaviour and physical activity. The majority of patients report one or more symptoms such as pain, fatigue and dumping. Negative affect and previous traumatic experiences, prevalent among people with obesity, have been found to modulate symptom perception. Few studies have explored these relationships in obesity surgery patients. Objectives: The first aim was to examine the self-reported frequency and impact of symptoms after surgery. The second aim was to prospectively explore the potential relationships between negative affect, traumatic events and level of symptom reporting. The third aim was to investigate whether change in negative affect predicted change in symptom perception. Methods: The data stems from the “Oslo Bariatric Surgery Study” (OBSS), an ongoing prospective study. The sample consists of 150 participants that underwent Roux-en-Y gastric bypass surgery at Oslo University Hospital, Aker, with self-report data before, one year, and three years after surgery. Patients rated 11 symptoms´ level of impact on behaviour. Negative affect was measured using the Hospital Anxiety & Depression Scale (HADS), and patients indicated if they had experienced any of four violent or sexual abusive events. Results: All participants reported symptoms three years after surgery. The most common symptoms were easily feeling full, dumping and fatigue. Being unemployed and having a history of traumatic life events were related to higher perceived impact of symptoms. Partial correlation analyses, controlled for weight loss, revealed positive, prospective and cross-sectional, relationships between negative affect and total number and impact of symptoms. Multiple linear regression analyses showed that increased anxiety symptoms from one year to three years after surgery predicted increased pain, and an increase in depressive symptoms predicted increased fatigue. Conclusion: This is one of the first studies to report a relationship between traumatic life events and negative affect, and symptom perception in obesity surgery patients. This provides new insight regarding how psychological factors relate to symptom reporting following gastric bypass surgery. Self-perceived symptoms are important targets for interventions.