The phrase "doing business as" (abbreviated DBA, dba or d/b/a) is a legal term used in the United States, meaning that the trade name, or fictitious business name, under which the business or operation is conducted and presented to the world is not the legal name of the legal person (or persons) who actually own it and are responsible for it. In other countries the expressions operating as (abbreviated o/a) or trading as (abbreviated T/A) are used for a similar purpose. The desired name might not have been registrable, or the business might be owned by another company, franchisee, or a sole proprietorship, resulting in all legally binding transactions taking place on behalf of the trading as name.

(im Deutschen wörtlich „Geschäfte tätigend als“) – abgekürzt DBA oder d/b/a – ist ein juristischer Begriff im Recht der Vereinigten Staaten. Er bedeutet, dass ein Unternehmen (juristische Person) oder Unternehmer (natürliche Person) Geschäfte unter einem anderen als seinen rechtmäßigen Namen tätigt.