Diamond-like carbon (DLC) has excellent mechanical properties and chemical stability. Several techniques have been proposed for DLC fabrication. The plasma-based ion implantation and deposition (PBIID) method has several advantages, such as few limitations in sample shape, in comparison with conventional PVD or CVD methods. We have investigated the cell adhesion to nitrogen-doped DLCs fabricated by the PBIID method. The cell adhesion percentage for a non-doped DLC was 67% and for nitrogen-doped DLCs the adhesion increased by more than 10%. The cell adhesion percentage was 85% for a sample with a ratio of nitrogen to carbon of 0.2. We consider the possibility that the cell adhesion percentage is improved due to C–N and N–H bonds that promote the protein adsorption on the surface of the sample.