The transport of folate by murine leukemia cells, hepatic cells, choroid plexus and intestine is a complicated process involving at least two different carrier-mediated processes and/or passive diffusion by certain cells. Although there are marked similarities between many of the models studied, there are also striking differences, especially with regards to specificity of the transport system. This review compares and contrasts these different systems as well as briefly examining the role of folate binders and newer techniques for studying folate and anti-folate delivery to cells.