Background and study purpose: Hilar cholangiocarcinoma, also known as Altemeier-Klatskin tumor, is a rare malignancy that arises in the confluence of the hepatic ducts of the porta hepatis. The prognosis is rather poor. Several lesions mimic these tumors and lead to a misdiagnosis, resulting in radical hepatic resections. These lesions are known as Klatskin-mimicking lesions. We present our experience with the diagnosis and treatment of pathological lesions that can mimic a perihilar cholangiocarcinoma and establish an algorithm of treatment Methods: For the current retrospective study, a prospectively established bile-duct tumor database was analyzed by selecting patients with a preoperative diagnosis of perihilar cholangiocarcinoma. Results: In the last 22 years (from January 1, 1996, to December 31, 2017), 73 patients who were referred to our tertiary center with a primary diagnosis of a Klatskin tumor were treated. All patients underwent a thorough evaluation before deciding upon the treatment. However, only 58 cases had a confirmed preoperative diagnosis of hilar cholangiocarcinoma in the final histopathological examination. The final diagnosis in 15 patients differed from the primary cause for referral and the lesions were regarded as Klatskin-mimicking lesions. Conclusions: Clinicians should always highly suspect Klatskin-mimicking lesions when they evaluate a patient for a possible hilar cholangiocarcinoma in order to avoid a misdiagnosis and propose a proper treatment.