A revised nomenclature for the polypeptides of respiratory syncytial (RS) virus has been devised on the basis of comparison of the Long, A2 and RSN-2 strains by slab-gel electrophoresis. Seven polypeptides, now designated VP200, VGP48, VPN41, VPP32, VPM27, VP25 and VP10, were observed in preparations of all three strains of RS virus, irrespective of the host cell of origin. In addition, a slowly migrating glycopolypeptide GP1 was prominent in partially purified RS virus of the Long and A2 strains obtained from Hep-2 cells, and to a lesser extent from BS-C-1 cells. In the case of the RSN-2 strain, this polypeptide was only resolved clearly in virus obtained from Hep-2 cells. GP1 was an atypical glycopolypeptide in that 35S-methionine incorporation was poor relative to 3H-glucosamine incorporation. The ts mutants of RS virus exhibited four distinct phenotypes with respect to intracellular polypeptide synthesis and antigen production of 39 degrees C. Mutants ts 17 (complementation group B') and ts 19 (group E) were almost completely restricted, suggesting defective early functions. Mutants ts A1 (group A), ts A7 (group C) and ts 1 (group D) synthesized antigen and polypeptides normally, but the amount of antigen at the cell surface was reduced, suggesting maturation defects. In addition, the VPP32 of ts 1 (group D) exhibited an aberrant mobility, confirming its viral specificity. The remaining mutants, representing groups B, F and G exhibited generally impaired synthesis at 39 degrees C. Absence of surface filaments in ts mutant-infected cells at 39 degrees C confirmed their virus-specific nature.