The osseous amyloidosis associated with a pleural effusion in a myeloma is a rare situation. We report a case of an association of these three disease entities for discussion. A 75-year-old man was admitted for chest pain and dyspnea with left sacred bone pain. The radiological assessment reported pleurisy and bilateral lytic images of the sacrum with soft tissue invasion, the biochemical tests showed a lambda free light chain myeloma and bone biopsy reported amyloidosis. The occurrence of systemic amyloidosis in myeloma is well documented, but the osseous location is rare and rarely revealed. Pleural effusion is a known complication of myeloma but is exceptionally revealing; it is usually seen in the myeloma IgG and IgA but very rarely in free light chain myeloma. We reported here a case that represents an exceptional situation of complications of light chains myeloma to remember their possible occurrence and to insist for the clinician sensitizing to carry out investigations on time and avoid complications or at minimum to retard them.