Apart from the local application, bone morphogenetic proteins (BMPs) have been systemically applied in rats for the following indications: bone formation in a model of osteoporosis [1], kidney regeneration in models of acute and chronic renal failure [2–7], liver regeneration [8], ischemic coronary infarction [6, 9] and stroke [10], and in a nude mouse model of human prostate, breast, brain and melanocyte cancer [11–14]. BMPs induced organ regeneration recapitulating embryonic development without recorded systemic side effects, except transient bone formation at the site of injection around the tail vein. This was not unexpected, since around the blood vessels the existing progenitor cells can differentiate into cartilage and bone in the presence of a recombinant BMP. No ossification of other tissues has been recorded even after a long period of daily BMP injections. The idea of using BMPs systemically for promoting tissue regeneration and repair has existed for years. However, do we have enough information on their pharmacodynamic and pharmacokinetic properties and a reproducible production of pure preparations for clinical use, and on reproducible results of their efficacy? Do BMPs circulate under physiological conditions? These questions are discussed in this chapter in an attempt to support evidence for their systemic use.