Pulmonary alveolar proteinosis is a rare idiopathic diffuse airspace disease characterized by intra-alveolar accumulation of large quantities of lipoproteinaceous material, with preservation of the lung interstitium. The clinical course of pulmonary alveolar proteinosis is variable. Spontaneous resolution is known to occur in up to a quarter of the cases. We describe two patients with untreated pulmonary alveolar proteinosis who experienced complete clinical, functional and radiographic resolution. In follow-up periods of fourteen and six years, both patients have remained asymptomatic.