A high performance liquid chromatography (HPLC) method is described for the separation of angiotensin (Ang) peptides and their subsequent quantification by radioimmunoassay in plasma and cerebrospinal fluid (CSF). The use of the ion-pair solvent heptafluorobutyric acid in gradient HPLC achieves baseline resolution of Ang I, Ang II, and the C-terminal fragments des-[Asp1]-Ang I, des-[Asp1]-Ang II, des-[Asp1,Arg2]-Ang II and des-[Asp1,Arg2,Val3]-Ang II in approximately 25 min. Recovery of synthetic Ang standards after phenylsilica extraction and HPLC separation was greater than 70% for each peptide in both plasma and CSF. Ang I and Ang II were shown to be the major immunoreactive Ang components in plasma, and Ang II, des-[Asp1,Arg2]-Ang II and des-[Asp1,Arg2,Val3]-Ang II in CSF.