An 18 year old woman with beta thalassaemia/haemoglobin E developed a large pelvic tumour resulting in bilateral obstructive uropathy. Technetium-99m sulphur colloid marrow image, computed tomographic scan of the abdomen and needle biopsy of the mass confirmed the diagnosis of extramedullary haematopoiesis. Although radiation is the treatment of choice for decompression, the mass in this patient did not respond satisfactorily due to its multiple area of tumour autoinfarction. Obstructive uropathy due to extramedullary erythropoiesis has not to our knowledge been previously described.