Polyacrylamide gels cross-linked with N,N′-diallyltartardiamide (DATD) are, in contrast to gels cross-linked with N,N′-methylenebisacrylamide (Bis), readily solubilized by periodic acid (Anker, H. S., 1970, FEBS Lett. 7, 293), thus permitting efficient analyses of electrophoretically separated, labeled biological material. The capacities of polyacrylamide gels, cross-linked with Bis and DATD, to serve as media for electrophoretic separation of proteins, were compared. As DATD-cross-linked gels were inferior to equimolar Bis-crosslinked gels with 5% cross-linking ( C Bis = 5%) by the criteria of more pronounced swelling, markedly softer gels and, less concentrated and bended protein zones on electrophoresis and subsequent staining, gels cross-linked with different percentage CDATD were examined. The water regain of DATD-cross-linked gels, the retardation coefficients, and free mobilities of different proteins in equimolar Bis- and DATD-cross-linked gels were determined. When the DATD concentration in gels was increased to C DATD = 27%, gels assumed physical characteristics comparable to those cross-linked with Bis at C Bis = 5%. We report further the rapid, facile isolation of protein bands out of the gel matrix cross-linked with DATD. However, the isolation procedure results in an irreversible loss of biological activity.