It has been reported recently that a number of cytokines, mainly tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta, and IL-6, can alter lipid metabolism and produce hyperlipidemia. Studies in hemodialysis (HD) patients have demonstrated increased production of these cytokines during HD. In order to investigate any possible relationship between changes of cytokines and lipid concentrations during HD in the serum of 25 uremic patients on chronic HD using modified cellulose membranes, TNFalpha, IL-1beta, IL-6, total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), lipoprotein a (Lp[a]), and total proteins were measured immediately before (pre-HD) and after HD (post-HD), in one session. The post-HD values were corrected according to the hemoconcentration based on the changes in serum total proteins. Serum TNFalpha and IL-1beta levels were significantly increased from 38.24 +/- 17.85 pg/ml and 2. 60 +/- 3.64 pg/ml pre-HD to 48.86 +/- 25.21 and 3.49 +/- 4.08 pg/ml post-HD, p < 0.001 and p < 0.05 respectively. Also Lp(a) levels presented a statistically significant increase post-HD and were almost doubled (pre-HD: 15.41 mg/dl, to post-HD: 27.39 mg/dl, p < 0. 05). Serum IL-6 as well as serum TC, TG, HDL-C, and LDL-C did not show any statistically significant alterations during HD. A significant positive correlation was detected between TNFalpha and Lp(a) values post-HD (r: 0.413, p: 0.04), but not between pre-HD values. No further relationship between serum cytokines and the other estimated lipid parameters was observed, either between pre- or post-HD values. Our results indicate that release of TNFalpha and IL-1beta during HD have no effect on serum lipids concentration, except on Lp(a). It seems that the acute rise of this lipoprotein during hemodialysis may be related with the TNFalpha overproduction.