Abstract In the present study, the biotribological response of CoCr alloys modified with boron was investigated. Four CoCr alloy compositions with different boron additions were prepared using an induction furnace. A ball-on-disc tribometer with a friction coefficient measurement system was used to evaluate the wear behaviour. The wear factors under different microstructural conditions were determined to solve the Archard wear equation. All samples were characterised using metallographic techniques, confocal microscopy, scanning electronic microscopy, energy dispersive spectroscopy, X-ray diffraction and roughness and hardness tests. Irritability tests in subcutaneous tissue were performed in rats (Rattus norvegicus) according to the standard ISO 10993 to determine the biocompatibility of the fabricated materials. The results showed that the addition of boron substantially modified the microstructure of the alloys, increasing the secondary hard phase content. Moreover, as the boron content increased, the wear resistance also increased. The irritability tests of the samples showed no evidence of macrophage cells or an inflammatory response at any boron content.