Phosphate (P) retention, resulted from renal insufficiency directly or indirectly provides pathogenetic roles to the human body. P related signs and symptoms include osteodystrophy, metastatic calcification, central or peripheral neuropathy, anemia, cardiomyopathy, lipid and carbohydrate mal-metabolisms, immunodysfunctions and so on. From these pathological effects of P, P is regarded as one of the major uremic toxins. In spite of the small molecular weight of P, P always shows lower dialysis efficiency than urea. This result can be partially explained by the interaction between negatively charged P and dialysis membrane. Although computer simulation model represented the increase in dialysis efficiency of P across the positively charged membranes, these membranes have not been clinically available. Dialysis membrane with larger membrane pore size and increased porosity significantly stimulated the P removal, however dialysis efficiency of P remained still lower than urea. From these results, it is strongly expected that membrane technology will succeed in the development of new dialysis membrane with more effective P removal.