Fouling of electrode surfaces by electrode reaction products or by biological spectator species is known to inactivate electrochemical sensors and thus limit their use in biological conditions. Here we present an investigation on the stability of boron doped diamond (BDD) electrodes with different levels of doping. Three different doping levels were used (0.1, 1 and 5% in the carbon phase). The highly doped (5%) BDD is of particular interest as it is here used for the first time for biological applications. Three different redox reactions were examined based on their electrode reaction characteristics: ruthenium(III) hexaammine (outer sphere), ferrocyanide (suface dependent), dopamine (adsorption mediated). The effect of albumin at blood concentration was studied. All results were compared with glassy carbon.