Studies of electrical stimulation of osteogenesis with stainless steel electrodes have previously established a dose-response relationship between current and bone growth. Examination of the effect of differing geometric current densities resulted in the conclusion that very little electrode surface area was involved in stimulation and led to the design of a multiport "distributive" cathode. A series of experiments were performed to extend these results to wire and multiport platinum electrodes. As before, a current-bone growth dose-response relationship was found. Peak bone growth was greater than for stainless steel. However, peak bone growth occurred at 2.0 microA (versus 20 microA for stainless steel). Correlation studies suggest that small changes in cathodic potential affect bone growth more than similar size changes in current. Finally, the generally benign local host response to platinum suggests that platinum may be a suitable material for chronic indwelling anodes for stimulation of osteogenesis.