Statin exposure has been associated with a broad spectrum of muscle toxicity, ranging from asymptomatic creatine kinase (CK) elevation to immune-mediated necrotizing myopathy (IMNM) with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) antibodies. The mechanisms underlying these adverse effects are not fully understood, and genetic predisposition may play a role. This observational study evaluated the association of HLA-DRB1*11 and SLCO1B1 rs4149056 variants with statin-induced muscle toxicity. A total of 62 statin-exposed patients treated at a single tertiary center were included and classified as follows: IMNM with anti-HMGCR antibodies (n = 11), non-immune myotoxicity (n = 20), and statin-exposed controls without myopathy (n = 31). The mean age was 66 ± 7.5 years, and 62% were women. The frequency of the HLA-DRB1*11 allele was significantly higher in patients with anti-HMGCR IMNM compared to those with non-immune myotoxicity (81.0% vs. 25.0%; OR = 13.5, 95% CI 1.73–15.3; p < 0.01) and controls (81.0% vs. 17.2%; OR = 21.6, 95% CI 2.87–23.7; p < 0.01). No significant difference was found between the non-immune myotoxicity and control groups. Likewise, the SLCO1B1 rs4149056 variant showed no association with either IMNM or non-immune muscle toxicity. These findings confirm a strong association between the HLA-DRB1*11 allele and anti-HMGCR IMNM. This genetic marker may help to better distinguish immune-mediated from non-immune forms of statin-related myopathy.