Introduction & Objective: Direct access to blood circulating system specially superficial veins in some emergency situation such as severe burning, severe edema, thrombosis in superficial veins, severe obesity and shock due to severe bleeding is difficult and in some cases impossible. So, in such situations other routes of injection should be used for fluid and drug infusion. In this study, the two routes of intravenous and intraosseous injection were evaluated in the case of adult rabbits with mature bones. Materials & Methods: This study was carried out, as an experimental study, on 20 adult white New Zealand rabbits with 4-6 month age. Methylen-blue was used to compare the two ways of intravenous and intraosseous injection, 10 rabbits received 5cc Methylen-blue intravenously and 10 rabbits received 5cc Methylen-blue intraosseously. Data were collected and analyzed by using appropriate frequency tables for the available data. Results: The average time of Methylen-blue appearance in the Aortic cannulation was 9.781±2.336 second for intraosseous injection and 10.052±2.336 seconds for intravenous injection. The difference was not statistically (Man Whitney) significant (P=0.800). Conclusions: It is seems that intraosseous injection has the same efficacy as the intravenous injection and we can use intraosseous injection route in adults when the vein is inaccessible.