VP4s from five Australian porcine rotaviruses (CRW-8, BEN-307, BMI-1, MDR-13, and TFR-41) were sequenced and analyzed. Strains with distinct VP7s were demonstrated to have closely related VP4s similar to OSU. However, MDR-13 which manifested both G3 and G5 specificity was found to contain a unique VP4 which contained 2388 nucleotides, six bases longer than the longest VP4 ever reportad. © 1993 Academic Press, Inc.