There is debate as to how much acetate in PD solutions influences the nUFV, so we decided to evaluate it during uncomplicated IPD and aseptic peritonitis connected with IPD treatment. In 8 patients dialysed with acetate (35 mmol/L) solutions for 9 +/- 8 months the nUFV (drainage volume minus instillation volume, mL/exchange) was calculated for 1.5 and 4.25% glucose exchanges during uncomplicated IPD and aseptic peritonitis. Then, lactate (35 mmol/L) buffered solutions were used instead of acetate ones and the nUFV was estimated under the same conditions. During uncomplicated IPD as well as peritonitis the nUFV was significantly higher in exchanges with lactate then with acetate solutions when the glucose concentration were comparable. In aseptic peritonitis the nUFV was less decreased with lactate than acetate solutions. We conclude during uncomplicated IPD or aseptic peritonitis in patients dialysed with acetate buffer the nUFV can be improved when acetate in PD solutions is substituted by lactate.