It is well known that in HD patients disorders of nutritional status and OS significantly contribute to all-cause and cardiovascular mortality in HD patients which is proven to be significantly higher in this group of patients than in general population. Aim of this study was to assess variability of markers of nutritional status and biomarkers of OS and their possible interactions during six months follow-up. Study included 45 patients, 70 years of age (60.5 -76.5 years) with median dialysis duration of 25 months (16-53.5 months). During follow-up we measured three times (June, October and Januar) anthropometric and biochemical parameters of nutritional status, body composition analysis and assessment of nutritional status using MIS and DMS nutritional questionnaire for HD patients. Further, OS analysis was performed by using tests showing oxidative damage like reactive oxygen metabolites (d-ROMs) and products of lipid peroxidation (TBARS) together with tests for assessing antioxidative defence like protein plasma reduced thiol content (THIOLS) and antioxidation capacity of plasma (FRAP) with levels of vitamin C. Also, study assessed influence of dialysis dose (measured with Kt/V and URR) and EPO dose on nutritional status and OS. Results showed that during follow-up there was a significant increase of body composition markers that reflect adipose tissue: FTI (P<0.001), FTM (P<0.001) and ATM (P<0.001), while simultaneously body composition markers that reflect nutritional status significantly decreased: LTI (P<0.001), LTM (P<0.001) i BCM (P<0.001) as well as overhydration (OH) (P=0.004). Fat tissue body composition markers FTI, FTM and ATM showed statistically significant positive correlation with BMI (ρ=0.711, P<0.001; ρ=0.738, P<0.001; ρ= 0.728, P<0.001), MUAC (ρ=0.455, P=0.01; ρ=0.503, P<0.001; ρ=0.503, P<0.001), waist circumference (ρ=0.571, P<0.01; ρ=0.649, P<0.001; ρ=0.649, P<0.001), hip circumference (ρ=0.648, P<0.001; ρ=0.758, P<0.001; ρ=0.752, P<0.001) and WHtR (ρ=0.641, P<0.001; ρ=0.631, P<.0.001; ρ=0.624, P<0.001). Additionally significant variations in levels of d-ROMs (P=0.02) and THIOLS (P=0.002) were found. Levels of d-ROMs significantly correlated with FTI (ρ=0.383, P=0.03) and FTM (ρ =0.387, P=0.03), and inflammation markers like leucocytes (ρ=0.417, P<0.001) and hs-CRP levels (ρ=0.571, p<0.001). Significant biochemical marker of nutritional status prealbumin significantly positively correlated with body composition parameters that reflect muscle mass: LTI (ρ=-0.434, P=0.01), LTM (ρ=-0.467, P=0.01) and BCM (ρ=-0.475, P=0.01). Parameters of dialysis dose Kt/V and URR significantly correlated with body composition markers that reflect muscle mass LTM (ρ=-0.444, P=0.01;ρ= -0.486, P=0.005) and BCM (ρ=-0.434, P=0.01; ρ=-0.476, P=0.006). Multivariant regression analysis found that hip circumference was the most significant predictor of d-ROMs levels (ß = 2.8; 95% CI 0.63- 5.04; P=0.01) and prealbumin was the most significant predictor for THIOLS level (ß = 263.9; 95% CI 6.8- 521.1; P=0.04). In conclusion, this study suggests significant interaction between markers of nutritional status and biomarkers of OS. Furthermore, there is potentially bidirectional relationship between biomarkers of OS and parameters of body composition, especially those parameters that reflect fat tissue.