This study was undertaken to provide investigators working in this particular research field with extensive and useful basic information based on an analysis of a large reliable series of cases regarding tracheal and bronchopulmonary carcinoids and their atypical varieties. A statistical evaluation was carried out which included a total of 1,875 patients with tracheal and bronchopulmonary carcinoids; these were divided into two series, one of 1,595 patients with typical carcinoids and the other of 280 with atypical varieties. These two series were compared regarding various aspects, which included the male to female ratio, age distribution, clinical manifestations, successful preoperative diagnosis, diagnostic accuracy of representative procedures, sites of involvement, tumor size distribution, metastases, carcinoid syndrome, serotonin activity in patients with or without the syndrome, immunohistochemistry, electron microscopy, and postoperative prognosis of the patients. The comparative analyses between the two series disclosed statistically significant differences (p<0.01) regarding various viewpoints; among others, such a difference was proved in the average age, sites of involvement in the lung (central or peripheral), rates and sites of metastases, adrenocorticotrophic hormone (ACTH) production, the association rate of the carcinoid syndrome, and postoperative 5-year and 10-year survival rates (93.3% and 82.1% for the typical carcinoid series versus 68.8% and 58.6% for the atypical variety series: p<0.0001). The postoperative 5-year and 10-year survival rates in the other two groups of patients with or without metastases were likewise calculated and showed a statistically significant difference (72.8% and 52.8% for the former versus 98.3% and 95.4% for the latter: p<0.0001).