Summary What is known and objective There is a disparity between the Korean treatment guidelines and actual clinical prescription habits. This study was designed to evaluate the department‐specific disparities and achievement rates for low‐density lipoprotein cholesterol (LDL‐C) targets, based on each department's specific statin prescription patterns. Methods We retrospectively evaluated data from 31 718 patients who had been prescribed a statin at least once between January 2008 and June 2013 at our institution. Patients were classified into the high‐risk (target LDL‐C < 100 mg/dL) or moderate‐risk (target LDL‐C < 130 mg/dL) groups, according to the National Cholesterol Education Programme‐Adult Treatment Panel III guidelines. Results and discussion Statins were most commonly prescribed in the cardiology (32·0%) and endocrinology (26·6%) departments. For the high‐risk group, 70% of patients in the cardiology, endocrinology and cardiac surgery departments achieved their target LDL‐C levels (<100 mg/dL). However, the target achievement rates in most other departments were <70%. For the moderate‐risk group, 79·2% of patients achieved their target levels. Departments that prescribed a greater number of high‐ or intermediate‐potency statins were more likely to achieve their target LDL‐C levels. The group that achieved their target LDL‐C levels (<100 mg/dL) exhibited a significant positive relationship (Spearman's correlation coefficient = 0·8571, P = 0·0065), from low to high potency. What is new and conclusion Some departments tend to undertreat when prescribing statins. However, to reach to the target LDL‐C levels, physicians must overcome their tendency to undertreat with statins. We believe that the target achievement rate will increase if doctors are more actively aware of a patient's individual status and related risk factors before prescribing statins. Some departments tend to undertreat when prescribing statins. To reach to the target LDL‐C levels, physicians must overcome their tendency to undertreat with statins.