Background: The true incidence of contralateral occult inguinal hernia (OIH) is a debate. The repair of contralateral OIH in the treatment context of clinical symptomatic unilateral inguinal hernia (IH) is controversial. This study aimed to assess the effect and clinical benefit of preoperative ultrasound (US) in the diagnosis of contralateral OIH performed before surgery. Methods: The retrospective data of 155 consecutive male patients who underwent IH repair between January 2014 and January 2020 were analyzed. The surgical procedures for IH and the clinical outcomes of the US were evaluated. Results: Of 155 patients, 29 (18.7%) presented with bilateral IH. Preoperative US was performed in 73 cases of clinical unilateral IH (n=126), and 30 (23.8%) patients were found to have a contralateral OIH. The totally extrapreperitoneal (TEP) or Lichtenstein repair was conducted. Bilateral IH repair was proposed for all, but only 28 agreed and underwent bilateral repair. Patients with clinically bilateral hernia had more complications compared with patients diagnosed to have occult contralateral IH after the US (n=3 vs. n=0). In the overall group, the TEP procedure resulted in shorter hospital stay (P=0.001) and less pain (P=0.021). Conclusions: The preoperative US may be recommended to assess the presence of a contralateral OIH as it is a noninvasive, radiation-free, widely available, relatively cheap diagnostic method. The preoperative US may change the surgical approach in up to 1/4 patients with a clinical unilateral IH. Either Lichtenstein repair or TEP repair can be performed with an acceptable complication rate in the case of OIH.