The amount of heat produced by dental implant osteotomy (receptor site) preparation at different speeds and the effects of heat production on the prognosis of implant treatment are controversial. In Part I of this two-part study, heat production was measured in vivo during osteotomy preparation at low (maximum 2,000 rpm), intermediate (maximum 30,000 rpm), and high (maximum 400,000 rpm) speeds in the rabbit tibia, and an inverse relationship was observed between drill speed and heat production. For the measurement of heat production (Part I), a thermocouple probe was inserted into a prepared receptor site in the anteromedial aspect of the tibial metaphysis. Temperature was recorded while an osteotomy was drilled 1 mm from the thermocouple receptor site. Distilled water was used as coolant in conjunction with all drilling, and all osteotomies were prepared by a single researcher to eliminate the variable of interoperator difference in technique. An inverse relationship was observed between drill speed and heat production. An analysis of variance indicated significant differences in heat production among the three drilling speeds (P 0.05). The results of Part 1 of this study indicate that for the configuration and material of bur used, the high-speed range minimizes heat production.