Adenocarcinoma of the esophagus is a well-known complication of Barrett's esophagus. This report describes five patients (three men and two women) with Barrett's esophagus and squamous carcinoma of the esophagus. All patients had hiatal hernia, and three had a history of tobacco and alcohol use. The tumors were located in the Barrett's mucosa in one case, at the squamocolumnar junction in two cases, and in the squamous-lined mucosa above the Barrett's mucosa in two cases. One patient also had focal adenocarcinoma associated with the squamous carcinoma of the esophagus. Review of the literature identified 11 previously reported cases. Occurrence of esophageal squamous carcinoma in Barrett's esophagus patients suggests a possible relationship between these two conditions, and the need for a careful evaluation of the squamous esophageal mucosa and the squamocolumnar junction at the time of endoscopy.