TP53 gene is an important early diagnostic cancer marker since it mutated in most type of human cancers and TP53 mutations have prognostic importance and sometimes are a significant factor in determining the response of tumours to therapy. A DNA-based piezoelectric biosensor has been developed for the detection of TP53 mutation using the new commercially available instrument QCMagic (Elbatech- Italy). This instrument with 9.5 MHz quartz crystals has been applied to the detection of TP53 point mutations (codon 248) in PCR amplified samples. The affinity reaction is based hybridisation reactions between the immobilised probe and a short sequence (26 mer) complementary, non-complementary and one-point mutation DNA were then investigated. The biosensor is first developed using synthetic oligonucleotides, studied in terms of the main analytical parameters (sensitivity, specificity, reproducibility, etc.) and then applied to the analysis of real samples consisting in amplified DNA extracted from "normal" wild type cell line (Jurkat) containing the fully complementary sequence and DNA extracted from cell line (Molt 4) containing the mismatch sequence.