In an earlier study we used various electrophoretic techniques to investigate the proteins in amniotic fluid, including two-dimensional electrophoresis. However, the high proportion of albumin dominated the pattern and tended to distort the pH gradient. Improved methodology, based upon the removal of albumin with Blue Sepharose CL6B and the silver-staining technique, has been used in the present work. These modifications have minimized problems of distortion. We have extended our work in a attempt to complete the two-dimensional map of the proteins in amniotic fluid. Over 200 proteins were seen, ranging in molecular mass from 10 000 to 100 000, including a relatively high proportion of polypeptides of low-molecular mass. The spots seen in the map are discussed in relation to some of the proteins, peptides, and hormones that have been reported in amniotic fluid. Eventually, it is hoped that polypeptides will be found that will provide better indicators of the condition of the fetus.