Objectives: An outbreak of acute gastroenteritis due to Shigella flexneri occurred in August 2012 in the catchment area of the Wadi Sahtan Health Center in Rustaq, Al Batinah South Governorate, Oman. The aim of this study was to discover possible causes of this outbreak in the villages of Fassa, Rogh and Amk and to measure the risk of exposure among cases and controls. Methods: A case-control study was conducted in September 2012 in Fassa, Rogh and Amk. All households in the three villages were interviewed. Case and control households were compared to determine possible exposure avenues, including place of residence, source of drinking water, hand hygiene levels and practices related to drinking water, food preparation and environmental sanitation. Results: Residing in Fassa (P <0.0001; odds ratio [OR] = 4.86, 95% confidence interval [CI] = 2.22–10.63) and average hand hygiene practices (P = 0.008; OR = 13.97, 95% CI = 1.58–123.36) were associated with an increased risk of contracting shigellosis. No significant differences were found with regards to the other exposure avenues. Conclusion: This was the first study conducted in Oman regarding an outbreak of shigellosis in a community setting. The only variables that significantly impacted the risk of acute gastroenteritis were residing in Fassa and average hand hygiene practices. The source of the outbreak could not be identified. However, septic tank sanitation and water and food consumption practices were not satisfactory in the studied villages. These need to be addressed to prevent similar outbreaks of acute gastroenteritis in this region in the future.