A case report of an unusual formaldehyde exposure that had happened accidentally is described. A 54-year-old male ingested 10% formaldehyde and inhaled while vomiting and he developed cough, dyspnea and wheezing with prevalent ronci and bilateral infiltrates on chest x-ray (cxr). His pulmonary symptoms and FEV1 responded well to systemic corticosteroids and nebulised salbutamol given for the possible diagnosis of hypersensitivity and/or chemical pneumonitis, and infiltrates were cleared. Two weeks after the incident, he had massive haemoptysis, fever, leucocytes, prevalent crackles, bronchospasm, and new infiltrates on CXR. After an antibiotic and steroid therapy, his symptoms and crackles relieved, radiographic infiltrates were regressed. Delayed type hypersensitivity to formaldehyde patch test was appropriate with late-onset symptoms. This is a first case of pneumonitis as well as asthma different from the occupational exposure to formaldehyde. This data suggests direct and indirect effects of formaldehyde in healthy human airways.