Most patients sensitive to soybean experience gastrointentinal symptoms, urticaria, angioedema, and asthma after ingestion. However, we report here a previously non-allergic patient who developed immediate and late onset asthma after breathing soybean flour used in the manufacture of food supplements. She exhibited positive immediate and late skin test sensitivity as well as a positive bronchial challenge to a soybean flour extract. In contrast to another patient with an anaphylactic response after soybean ingestion, the radioallergosorbent test (RAST) to soybean antigen was negative in our patient.