The overall objective of the proposed project is to design, develop and construct a bone marrow separation device that will offer significantly superior performance compared with current methods of velocity sedimentation. In Phase I Technical Research Associates (TRA) will apply patented pseudo-standing wave ultrasound technologies to separate bone marrow cells by size. This novel device will eliminate the traditional cell concentration problem referred to as the """"""""streaming limit"""""""" associated with velocity sedimentation, using an acoustically inverted separation column. Using safe levels of ultrasound the forces generated by TRA's ultrasonic means are significantly higher than traditional """"""""g"""""""" forces and will effect rapid cell separation. The use of ultrasonically generated velocity gradients will also eliminate the need for the tedious and difficult formation of density when integrated into commercial separation systems, will provide more efficient collection of specific bone marrow and other biological cells for clinical treatment. The device will also save time, decrease costs and provide unique performance for those interested in fractionation of bulk quantities of cells (or bone marrow components).