Klinefelter syndrome (KS) is a hypergonadotropic hypogonadism characterized by a 47, XXY karyotype. The risk of testicular cancer in KS is of interest in relation to theories about testicular cancer etiology generally; nevertheless it seems to be low. We evaluated the need for imaging and serum tumor markers for testicular cancer screening in KS. Participants were 40 consecutive KS patients, enrolled from December 2009 to January 2013. Lactate dehydrogenase (LDH), alpha?fetoprotein (AFP), and beta?human chorionic gonadotrophin subunit (β?HCG) serum levels assays and testicular ultrasound (US) with color Doppler, were carried out at study entry, after 6 months and every year for 3 years. Abdominal magnetic resonance (MR) was performed in KS when testicular US showed micro?calcifications, testicular nodules and cysts. Nearly 62% of the KS had regular testicular echotexture, 37.5% showed an irregular echotexture and 17.5% had micro?calcifications and cysts. Eighty seven percent of KS had a regular vascular pattern, 12.5% varicocele, 12.5% nodules 1 cm. MR ruled out the diagnosis of cancer in all KS with testicular micro calcifications, nodules and cysts. No significant variations in LDH, AFP, and β?HCG levels and in US pattern have been detected during follow?up. We compared serum tumor markers and US pattern between KS with and without cryptorchidism and no statistical differences were found. We did not find testicular cancer in KS, and testicular US, tumor markers and MR were, in selected cases, useful tools for correctly discriminating benign from malignant lesions.