Purpose: Skin hyperpigmentation in end stage renal disease patients is known to be attributed to the accumulation of middle molecular weight (MMW) substances such as urochromic pigments and carotenoids. Therefore, there is a possibility that hyperpigmentation may be improved by high-flux hemodialysis (HF-HD) and online hemodiafiltration (HDF). This prospective study was undertaken to investigate the quantitative changes in skin color in HD patients according to dialysis modality. Methods: Eighty-two stable ESRD patients undergoing HD were enrolled and divided into three groups according to their dialysis modality. Melanin index and erythema index of forearm and abdomen (non-sun exposed area), and forehead (sun exposed area) were measured by narrow-band reflectance spectrophotometer at baseline and after 12 months. Results: There were no significant differences in the baseline values of melanin and erythema indices among the three groups. But the changes in forehead melanin index were significantly lower in HDF patients (-1.0±2.4%) compared to the LF-HD group (0.3±1.6%) (p<0.05), and forehead erythema index was significantly decreased in patients treated by HDF (-1.6±2.5%) relative to the low-flux hemodialysis group (-0.1±2.5%) (p<0.05). Conclusion: The changes in skin color of sun exposed area were reduced by HDF, suggesting that enhanced removal of MMW substances by convective therapy may be of advantage to skin hyper-pigmentation in ESRD patients