Human IGFBP-4 antiserum is a polyclonal antiserum raised against a synthetic peptide corresponding to amino acids 117-130 (Zapf, J. (1995) Eur. J. Endocrinol. 132, 645-654) of human IGFBP-4. This antiserum is suitable for use for ELISA and Western blotting and should find application for immunohistochemistry. The antiserum has been tested with and does not crossreact with human IGFBP-1, IGFBP-2 or IGFBP-3. Can be used at a dilution of 1/2,000 in ELISA. Half-maximal inhibition (ED50) is produced by 17 ng hIGFBP-4 / 100 μl. For Western blotting use a dilution of 1/1,000.