OBJECTIVE Chronic obstructive sialadenitis (COS) is a recurring inflammation of the salivary gland. To date, there are no known predisposing factors for COS. Given the advances seen in radiology and sialendoscopy, we must update our knowledge of COS, analyzing factors that can favor its development. METHODS We prospectively analyzed 333 patients who underwent sialendoscopy between 2012 and 2021. Epidemiologic, radiologic, and sialendoscopy-related factors were correlated. Suspected diagnosis was established based on the clinical and radiologic data. The final diagnosis was determined on the basis of sialendoscopic findings. RESULTS The most common etiology of COS was stricture (40.8%). Lack of papilla distensibility (LPD) was also described as an etiology. COS was related to patient gender and age. Submandibular gland involvement was significantly more associated with lithiasis and LPD, while COS of the parotid gland was most frequently caused by stricture. Radioiodine sialadenitis and Sjögren's syndrome were significantly associated with stricture. MR sialography (MR-Si) showed the best overall sensitivity and specificity. CONCLUSIONS In our series, stricture was the most common cause of COS. We describe LPD as a frequent cause of COS in this series; ours is the first study to report this finding. There was a significant association between the salivary gland involved, patient sex and age, and the cause of COS. MR-Si showed the greatest diagnostic yield.