Four new rare inherited variants (Pi types) of alpha 1-antitrypsin (alpha 1-protease inhibitor) are described. Each variant has been compared with previously reported genetic variants by several techniques used for Pi typing: isoelectric focusing in polyacrylamide gel, starch gel electrophoresis, and agarose gel electrophoresis. Some variants are identical or very similar by one technique but can be clearly distinguished by another technique. Crossed immunoelectrophoresis and gel immunofixation have been used to identify the gel bands as alpha 1-antitrypsin.