An apparatus for transferring beads employed in a radioimmunoassay is disclosed. The apparatus comprises a receptacle tray 30, test tube rack 48 and plurality of test tubes 42. The receptacle tray 30 contains an array of wells 32, which may be marked individually with indicia such as numerals and colors, and two alignment holes 34 and 35. The test tube rack 48 contains an array of columns 51 in a pattern corresponding to that of the wells 32 on tray 30. Test tube rack 48 also contains two alignment pins 52 and 53 for insertion into alignment holes 34, 35. Each of the test tubes 42 are generally cylindrical but have a gradually increasing diameter from bottom to top so that they can be inserted into rack columns 51 with a friction fit.