Features distinguishing secondary achalasia from primary achalasia. Eighteen patients with cancer-induced or secondary achalasia (SA) were compared to 421 patients with idiopathic or primary achalasia (PA). The aim of the study was to detect any differences in clinical presentation between the two groups. Mean age of patients with SA was 57.1 (range 15-78) and 47.1 (range 1-90) in patients with PA (p = 0.02). Three patients with SA were 15, 24, and 36 yr old, respectively. Symptom frequency was comparable in SA versus PA. Mean duration of symptoms in SA was 4.5 months, with 15 of the 18 patients experiencing symptoms for six months or less. Weight loss occurred in 88.2% of patients with SA and 57.3% of patients with PA (p less than 0.05). Cancer was at the gastroesophageal junction in 16 patients, duodenum in one, and breast in one. Endoscopy showed tumor in 12 (67%). The esophagram was suspicious for tumor in only 25%. We conclude that patients with SA are older, more likely to lose weight, and have a short duration of symptoms. However, SA may occur in younger patients, and endoscopy with biopsy is necessary in any newly diagnosed case of achalasia. 