This paper describes the differences among three business-oriented vocabularies collected from the following three sources: (1) textbooks used in a radio Business English program—“NHK Business Eigo;” (2) TOEIC practice tests; and (3) British National Corpus (BNC) spoken data taken from business meetings, consultations, and interviews. After generating three word lists from each corpus, the following four comparisons were made: (1) computation of the percentage of common words among the three vocabularies; (2) examination of the three specialized vocabularies extracted from each corpus by use of statistical measures such as log-likelihood ratio (LLR) and mutual information (MI); (3) assessment of each vocabulary level; (4) and calculation of the percentage of known words in each vocabulary learned from English textbooks in junior and senior high schools. This study revealed interesting and beneficial features of the three business-oriented vocabularies both qualitatively and quantitatively. 1. Background