A controlled trial of hepatitis B vaccination with recombinant antigen was undertaken in 18 hemodialysed end-stage renal failure (ESRD) patients (P) and 16 members of our staff (controls, C). In order to identify expected nonresponders (NR), we monitored T lymphocyte (Tc) subsets, peripheral blood mononuclear cells (PBMC), total leukocytes (WBC) and IgG. After 3 vaccine doses of 40 and 20 IU, respectively, for P and C, at 0,1 and 6 months, 11 P (61.1%) and all C (100%) responded, as in previous reports [1-3]. The 7 NR presented lower CD4 + Tc fraction, compared to responders (R) and C (p < 0.05), and higher monocyte (p < 0.00001) and WBC (p < 0.002) counts, with lower lymphocyte fraction (p < 0.001), compared to R. We suggest that NR could represent a selected group of ESRD patients, screenable by these easily detectable features, probably markers of a specific immune dysfunction.