Blood collection tubes containing separator gel are widely used in many clinical laboratories because of easy to use, convenience and several other advantages. However, they are not void of limitation. We describe an unusual case with a floating separator gel in the primary blood collection tube. The blood sample was collected into a BD Vacutainer SST II Advance tube, from a 51 years old man admitted for community acquired pneumonia and had history of hyperproteinaemia. Inappropriate positioning of the separator gel was observed after centrifugation, whereby the separator gel floated above the serum. Detection of abnormal separator gel floatation pattern in this patient’s sample before analysis had prevented potential technical problem and production of erroneous result caused by aspiration of separator gel. The limitation of blood collection tube with separator gel especially in patients with hyperproteinaemia should be made aware among laboratory personnel and physicians.