Background: Patients with end stage renal disease (ESRD) have increased inflammatory and thrombotic activity. Lacks of available data exist on pro-inflammatory and prothrombotic properties of low serum 25-OH-D3 level. We aimed to analyse the association of 25-OH vitamin D with indirect markers of inflammatory and thrombotic activity in patients on haemodialysis (HD) or peritoneal dialysis (PD). Methods: A total of 104 patients with ESRD receivin g renal replacement therapy (RRT) were enrolled into this prospective study. Seventy patients on HD and 34 age matched patients on PD with similar duration of ESRD and RRT were from same geographical area and had similar sunlight exposure. The mean age of patients on HD and PD were 56.59 ± 18.19 years and 53.26 ± 10.6 years; respectively. Fasting blood samples were obtained before dialysis session to analyse serum creatinine, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), leukocyte count, platelet count, platecrit (PCT), haemoglobin, haematocrit and 25-OH-D3. Results: There was no significant difference between patients on PD and HD in terms of serum calcium, phosphorus, parathormon, CRP, ESR, ferritin and bicarbonate levels. Patients on PD had significantly lower level of 25-OH-D3 (9.35 ± 7.69 vs 4.71 ± 3.01, p: 0.0001). Leukocyte count, platelet count, haemoglobin, haematocrit, RDW, neutrophil ratio, monocyte ratio, neutrophil count and PCT were significantly higher in PD patients (p: 0.001, p<0.001, p<0.001, p: 0.002, p: 0.020, p: 0.034, p: 0.009, p: 0.001, p: 0.001; respectively). There was a significant association between 25 hydroxy vitamin D3 with, CRP, ESR and haematocrit in PD group but not in HD group (p:0.019, p:0.002, p:0.025 respectively). Female patients in both groups had lower 25-OH-D3 level than male dialysis patients (p: 0.0001). Multiple regression analysis revealed out a significant effect of CRP, sedimentation, haematocrit, platelet count and PCT on D vitamin level (p: 0.022). Conclusion: Low serum 25-OH-D3 level reflects increased inflammatory and platelet activity in PD patients.