Five college students in Lewisburg, Pa, were accidentally exposed to two highly toxic chemicals, ethylenimine and N-ethylethylenimine, for two hours in a poorly ventilated fraternity-house room. Their complaints, delayed in onset from 3 to 71/2 hours after exposure, were severe soreness of the throat, severe eye irritation, vomiting, and coughing. Consistent clinical findings were conjunctivitis, upper and lower respiratory tract inflammation, transitory polycythemia, leukocytosis, eosinophilia, and albuminuria. Treatment included antihistamines, hydration, topical and systemic steroids, antibiotics, cough preparations, and enzyme therapy. All five students were free of symptoms within six months.