FGFR1 gene amplification is frequently observed in malignant tumors e.g. breast and prostate cancer and oral squamous cell carcinoma (OSCC). The FGFR1 (fibroblast growth factor receptor 1) gene is located in the chromosomal region 8p11.23-p11.22 and encodes a transmembrane receptor tyrosine kinase. Amplification of the FGFR1 gene, observed in approximately 10% of all breast cancer samples, has revealed to be an independent prognostic factor for overall survival. FGFR1 is believed to emerge as a potential therapeutic target for lobular breast carcinomas. In prostate cancer, FGFR1 gene amplification seems to be an important step during the transmission to hormone resistance. In OSCC, FGFR1 gene amplification, observed in nearly 20% of all cases, is indicated to contribute to oral carcinogenesis at an early stage of development.