OBJECTIVES: Severe asthma is found in approximately 10% of patients with asthma. Some factors associated with worse asthma control include rhinitis, gastroesophageal reflux disease, vocal cord dysfunction (VCD), nasal polyposis and bronchiectasis. Therefore, we evaluated the prevalence of these illnesses in patients with severe asthma. METHODS: We conducted a retrospective analysis of data obtained from electronic medical records of patients with severe asthma between January 2006 and June 2008. Symptoms of rhinitis and gastroesophageal reflux disease were evaluated as well as intolerance to nonsteroidal anti-inflammatory drugs. We evaluated the results of esophagogastroduodenoscopy, videolaryngoscopy and CT scans of the chest in order to confirm gastroesophageal reflux disease, nasal polyposis, vocal cord dysfunction and bronchiectasis. RESULTS: We evaluated 245 patients. Rhinitis symptoms were present in 224 patients (91.4%); 18 (7.3%) had intolerance to nonsteroidal anti-inflammatory drugs, and 8 (3.3%) had nasal polyposis. Symptoms of gastroesophageal reflux disease were reported for 173 (70.6%) patients, although the diagnosis of gastroesophageal reflux disease was confirmed based on esophagogastroduodenoscopy or laryngoscopy findings in just 58 (33.6%) patients. Vocal cord dysfunction was suspected in 16 (6.5%) and confirmed through laryngoscopy in 4 (1.6%). The patient records provided CT scans of the chest for 105 patients, and 26 (24.8%) showed bronchiectasis. DISCUSSION: Rhinitis and gastroesophageal reflux disease were the most common comorbidities observed, in addition to bronchiectasis. Therefore, in patients with severe asthma, associated diseases should be investigated as the cause of respiratory symptoms and uncontrolled asthma.