© 2020 Informa UK Limited, trading as Taylor & Francis Group.Purpose: Familial hypercholesterolemia (FH) is a genetic disease characterized by increased levels of low-density lipoprotein cholesterol (LDL-C). It is underdiagnosed and undertreated despite relatively high prevalance and significant association with increased mortality. We aimed to determine treatment status and compliance in patients with LDL-C ≥ 250 mg/dL and FH. Design: Patients older than 18 years old and have a serum LDL-C ≥ 250 mg/dL between January 2010 to December 2016 were identified from the hospital database. A phone survey was performed. Demographic features, smoking status, alcohol use, exercise, cardiovascular disease (CVD), use of medication for dyslipidemia, and CVD and high cholesterol levels in the family were questioned. Dutch Lipid Clinical Network Criteria was used to classify patients. The study was registered to Clinicaltrials.gov in July 2020 (NCT04494464). Results: 1365 patients with a LDL-C ≥ 250 mg/dL were identified. Patients that could not be reached and who refused to interview were excluded and the data of 367 patients were analyzed. There were 248 (67.6%) female and 119 (32.4%) male patients and mean age was 50.52 ± 11.66. LDL-C was ≥330 mg/dL in 50 (13.6%) and 250–329 mg/dL in 317 (86.4%) patients. Forty (10.9%) patients were classified as definite, 181 (49.3%) as probable and 146 (39.8%) as possible FH. 213 (58.0%) patients were not receiving lipid-lowering treatment, and 162 (76.1%) stated that medication was never recommended previously, 30 (14.1%) had stopped medication him/herself and 21 (9.8%) had stopped medication with the advice of the physician. Among patients with definite/probable FH, 84 (38.0%) had CVD and the rate of lipid-lowering drug use in these patients was 58.3%. Conclusion: A significant proportion of patients with LDL-C ≥ 250 mg/dL were not taking lipid-lowering drugs. Similar with many other studies, diagnosis, and treatment rates of FH patients were very low in our study. Further national studies are required to increase awareness of the disease in both physicians and patients.