Sir,The recent report on filariais and pleural effusion is very interesting.[1] In the present case, Navaz et al. reported for a case of isolated pleural effusion of filarial etiology.[1] In fact, the finding of filarial parasite in pleural cavity is rare and there might be other underlying disclosed pathology. As noted, the concomitant presentation with malignancy should be kept in mind.[2] In case with signs and symptoms of malignancy, especially for extremely weight loss, seeking for the malignancy is needed. Nevertheless, the detection of malignant cell within pleural fluid is difficult and requires the experience of the microscopist. Detection of parasite can be easier and this might lead to the misdiagnosis of malignancy.