Clostebol is a synthetic anabolic androgenic steroid, with potential use as a performance-enhancing drug if taken for long periods in order to produce the desired effect. Recently, the use of medications containing clostebol acetate has led to the suspension of several athletes in various sports. Previous studies have shown that urine can result positive in case of single intake of a banned substance, including unintentional consumption of steroids. In this context, a hair test can contribute to exculpation of athletes by demonstrating alternative administration or contamination. The development and validation of an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to detect clostebol and clostebol acetate in hair is hereby presented. Some real cases of athletes sanctioned for clostebol use, in which we analyzed hair samples to follow up investigations of doping control laboratories and obtain useful elements to understand the origin of clostebol intakes, and two forensic cases of anabolic drugs abuse, are also presented and discussed. In real head- and body-hair samples, clostebol acetate could be detected in the low pg/mg range. As is typical of hair analysis, the interpretation of the quantitative findings may be challenging, and even more in sports owing to the lack of systematic studies. However, the results can be used to produce evidence contrary to any ruling issued against the athletes by the appropriate sports body, and possibly obtain a diminished sanction. Because the sports authorities do not make a distinction among circumstances or means of administration of anabolic compounds, athletes should be warned not to use clostebol-containing medications.