Intra-dialytic hypertension is a well-recognized phenomenon which may have prognostic significance. There is however no accepted definition yet which hampers the assessment of its prevalence. Whereas various factors might be involved in its pathogenesis, available evidence suggests that volume overload appears to be the most important modifiable pathogenetic factor. There is need for more information about the pathophysiologic mechanisms, the prognostic meaning and the best treatment approach of intra-dialytic hypertension, coming from well conducted randomized controlled clinical studies. In the meantime, close attention to volume status remains the most important preventive and therapeutic tool.