A single intratracheal 0.1‐ml instillation of a calcium‐arsenate containing vineyard pesticide induced multi‐focal bronchogenic adenocarcinomas and bronchiolar‐alveolar‐cell carcinomas in nine out of 15 treated BD rats. This seems to be the first experimental confirmation of carcinogenicity of arsenic‐containing pesticides used formerly in vineyards. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company