Five carbobenzoxylated and D-amino acid containing-peptide analogs of the respiratory syncytial virus (RSV) F1 glycoprotein amino terminus were chemically synthesized by solution and FMOC-solid phase peptide synthesis methods. Several of these peptides, ranging from 3 to 6 residues in length, raised the bilayer to hexagonal phase transition temperature of dielaidoylphosphatidylethanolamine. None of these peptides were specific inhibitors of RSV or herpes simplex virus infection. Two of the series, CBZ-D-Phe-L-Leu-Gly-D-Phe-D-Leu-D-Leu and CBZ-D-Phe-L-Leu-Gly-D-Phe-D-Leu-D-Leu-Gly, were active in reducing measles virus-induced cytopathic effect at 62 micrograms/mL. Others in the series showed some activity at higher doses or activity simultaneously with some cell toxicity. These results support the view that membrane-stabilizing agents may have non-specific effects on membranes which are responsible for their antimeasles activity.