Deep vein thrombosis and pulmonary amboius are well known complications of lengthy orthopaedic procedures. Historically spine surgery has been associated with few thrombotic complications. Recent widespread use of instrumentation in adult cases led to concern regarding the incidence of deep vein thrombosis and pulmonary ambolus. Forty-one patients underwent posterior spinal procedures using either pedicular or segmantal Instrumentation. One day before discharge all patients underwent noninvasive testing using color duptex Doppler imaging to rule out deep vein thrombosis. Six patients were noted to have tests results compatible with deep vein thrombosis. The incidence of deep vein thrombosis during this study (14%) reveals a group of patients who would have been discharged with ongoing thrombosis and potential pulmonary embolism.