Saliva plays a major role in preserving the integrity of oral tissues. The oral health of renal failure patients could be negatively affected by the underlying pathology, the dialysis treatment, or an altered salivary composition. Major systemic changes occur during hemodialysis (HD), which could affect the flow rate and biochemical composition of saliva. Therefore, the aim of this study was to evaluate the effects of HD on the salivary flow rate, pH and biochemical composition before and after completion of a dialysis session. Thirty Renal failure patients undergoing hemodialysis were selected based on the inclusion and exclusion criteria set forth for the study. Unstimulated whole saliva (UWS) was collected by the spitting method, immediately before and after a dialysis session. Salivary flow rate, pH, concentration of urea, creatinine, sodium, chloride, potassium and calcium were measured. Hemodialysis had an acute stimulating effect on the salivary flow rate. The mean pH of UWS showed no significant changes before and after dialysis. The concentrations of urea, creatinine, chloride and potassium in whole saliva changed markedly before and after a hemodialysis session; whereas no significant difference was seen in the concentration of sodium and calcium. This study shows that HD has significant acute effects on both salivary secretion and biochemical composition in saliva. We conclude that the observed changes in salivary concentrations and flow rate are mainly due to an increased watery secretion from the salivary glands and also saliva can be used as a tool for monitoring hemodialysis.