Anergic response to tuberculin (PPD) is well known in haemodialysis patients (HDp). This cross-sectional controlled study was conducted to analyse the correlation of PPD response with demographical features, nutritional parameters and the distribution of peripheral blood lymphocyte (PBL) subtypes. In this study 29 HDp (17 men, 12 women; mean age 30.9 +/- 9.5 years) and 13 controls (eight men, five women; mean age 29.2 +/- 6.4 years) were included. The mean time spent on dialysis was 20.5 +/- 17.4 months. The mean PPD response was lower in HDp than controls (7.5 +/- 8 mm vs. 15 +/- 4 mm, P = 0.001). Fourteen patients (48%) were PPD (-) (eight men, six women; mean age 34.1 +/- 11.1 years) and 15 were PPD (+) (normergic) (nine men, six women; mean age 26.8 +/- 3.4 years). No difference was observed between PPD (-) and (+) groups for age, sex and time spent on dialysis. As nutritional parameters, body mass index, serum albumin, creatinine and cholesterol levels were measured and no differences were found between controls and the PPD (-) and (+) groups. Absolute lymphocyte counts were lower in HDP compared to controls (1290 +/- 296 vs. 1570 +/- 307 cells ml-1; P = 0.01). PBL subtype percentages and absolute counts (CD3, CD4, CD8, CD4/CD8, HLADR+CD3+, CD16+56+, CD19) were also similar between PPD(-) and (+) HDp. It was concluded that PPD response cannot be predicted by the distribution of PBL subtypes. The most probable cause of this observation is regulation of PPD reactivity by in situ immune cells whose composition is not reflected in the distribution of PBL.