Predictions of in vivo degradation behavior derived from laboratory experiments are of great importance in the development of biodegradable materials. A key issue is the simulation of the physiological conditions found in living organisms. Generally, the testing solution and in particular the pH buffer have a significant influence on the outcome of degradation experiments. This study presents results obtained from immersion tests in SBF buffered with gaseous CO2. The control of the pH value by means of CO2 has the advantage of better reflecting physiological conditions, and allows the carrying out of in vitro experiments which are closer to the in vivo situation.