Maffucci 's syndrome (MS) is a congenital non-hereditary mesodermal dysplasia characterised by numerous mesenchymal neoplasias in the form of enchondromas with secondary bone deformities and multiple soft tissue haemangiomas that may have phlebolitis. A 23-year-old male patient presented with non-productive cough, dyspnoea, chest pain and back pain. Chest X-ray showed unilateral pleural effusion and multiple enchondromas of the ribs. On physical examination, there were mobile, multiple, bluish-coloured lesions probably cavernous haemangiomas on bilateral chest walls. In addition, there were multiple nodular lesions on the extremities especially accumulated on the fingers. The patient was diagnosed as Maffucci 's syndrome according to computed tomography (CT) of the thorax, conventional radiography of the skeletal system, magnetic resonance (MR) imaging, Th4-Th11 intercostal and right upper extremity angiography and physical examination findings. As the patient rejected any diagnostic intervention, he was monitored with CT. During the last 6 years of follow-up, the lesion that was detected on the rib adjacent to the basal segments of the left lung showed significant progression and was accepted as chondrosarcoma. To our knowledge, this is the first case of Maffucci ' s syndrome with pleural effusion. In this case report, the probable mechanism of pleural effusion was discussed.