Amoeboid cell motility is a complex three-dimensional process which involves pseudopod expansion, cellular translocation, and, in some cases, pseudopod retraction and complex interactions between the ventral surface of the pseudopod and substratum. In order to quantify the basic behavior of amoeboid cells and the dynamics of pseudopod extension and retraction, sophisticated two-dimensional and three-dimensional computer-assisted motion analysis systems have been developed which reconstruct digitized images and compute motility and dynamics morphology parameters. These systems provide a wealth of information of how amoeboid cells crawl and they have begun to be utilized (1) to elucidate the basic rules of amoeboid movement, (2) to identify the behavioral defects of cytoskeletal mutants, and (3) to elucidate the mechanism of chemotaxis. In addition, these systems represent powerful tools for analyzing the effects of drugs on cell behavior, most notably that of white blood cells and neoplastic cells. Since computer-assisted motion analysis is a relatively young field, the technologies are still evolving and have been underutilized in most areas involving cell motility. This review, which includes a description of these technologies and examples of their application, will hopefully serve as an impetus for expanded use.