The purpose of the present report was to examine whether proprotein convertase subtilisin/kexin type 9 (PCSK9) levels differ in individuals who do not exhibit expected reductions in low density lipoprotein cholesterol (LDL-C) with statin therapy. Eighteen nonresponder subjects treated with 80 mg atorvastatin treatment for 6 months without substantial reductions in LDL-C (ΔLDL-C: 2.6 ± 11.4%) were compared to age- and gender-matched atorvastatin responders (ΔLDL-C: 50.7 ± 8.5%) and placebo-treated subjects (ΔLDL-C: 9.9 ± 21.5%). Free PCSK9 was marginally higher in nonresponders at baseline (P = 0.07) and significantly higher in atorvastatin responders after 6 months of treatment (P = 0.04). The change in free PCSK9 over 6 months with statin treatment was higher (P < 0.01) in atorvastatin responders (134.2 ± 131.5 ng/mL post- versus prestudy) than in either the nonresponders (39.9 ± 87.8 ng/mL) or placebo subjects (27.8 ± 97.6 ng/mL). Drug compliance was not lower in the nonresponders as assessed by pill counts and poststudy plasma atorvastatin levels. Serum PCSK9 levels, both at baseline and in response to statin therapy, may differentiate individuals who do versus those who do not respond to statin treatment.