Nanocrystalline diamond (NCD) films are deposited on silicon substrates using Microwave Plasma Enhanced Chemical Vapor Deposition technique with the variation of microwave power from 800 W to 1800 W at 200 mbar for 5 hrs. Methane is used as a precursor along with argon and hydrogen as carriers for deposition. Deposited films are characterized by using Raman, FTIR, optical contact angle, AFM and SEM. The biocompatibility study has been carried out by cell viability assay, haemolysis test and simulated body fluid (SBF) adsorption assay. The Lymphocytes and Fibroblast cell lines are cultured on the NCD coated samples and cell viability has been determined by MTT assay. The surface morphology of the samples has been studied by using AFM, before and after interaction with SBF. It has been observed that NCD coated substrates are biocompatible, haemocompatible and also promote the growth of the cells, while the uncoated substrates cause cell death.