Patients with chronic lymphocytic leukemia or non-Hodgkin’s lymphoma are at risk of infectious diseases of respiratory system because of immunodeficiency. Occurrence of organizing pneumonia in leukemic patients is most commonly correlated with bone marrow transplant or treatment with antimitotic agents. There have been only four reported cases of organizing pneumonia related solitarily to leukemia or lymphoma. We present a case of 65-year old gentlemen, diagnosed 8 months earlier with B-cell chronic lymphocytic leukemia with no previous hematologic treatment, who presented symptoms of persistent pneumonia with no significant reaction to antibiotics. Chest computed tomography scans showed well-localized consolidation with ground glass opacities and some air bronchogram, suggesting infectious disease. All results of microbiological examinations were negative. Due to radiological progression of parenchymal consolidation despite two intravenous courses of antibiotics open lung biopsy was performed. The histologic examination of lung specimen revealed structures typical for organizing pneumonia pattern. There was no evidence for leukemic involvement in lung tissue, as no sign for infectious factors from histological staining was observed. In the inferior mediastinal lymph node sample progression of chronic lymphatic leukemia to mixed cell lymphoma was diagnosed. Patient was commenced on prednisone 60 mg/daily with fast improvement. We believe that this is the first case of organizing pneumonia as a reaction to the conversion of B-cell chronic lymphocytic leukemia progression to more malignant stage.