Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by the accumulation of lipoproteinaceous material within the alveoli. Though many studies addressed biochemical data in bronchoalveolar lavage (BAL) effluent, poor attention was payed to cell profile in PAP. We report the case of a 40 year old woman, presenting with progressive respiratory failure and bilateral pulmonary infiltrates. BAL and transbronchial biopsy confirmed PAP. Therapeutic whole lung lavage led to full clinical and radiological remission. Sequential BAL follow-up was started over a 4-year period. As previously reported, lymphocytes were increased prior to whole lung lavage. This pattern subsequently remained, whereas recurrence or superinfections did not occur. The mechanism of this disorder is unclear and deserves further investigation.