Cerebrotendinous xanthomatosis (CTX) is a rare genetic disorder of bile acid synthesis. Disease progression in CTX can be effectively prevented by treatment with chenodeoxycholic acid (CDCA). Data from population-based genetic studies suggests CTX patients as a group are likely under-diagnosed. Those who are eventually diagnosed with CTX often remain undiagnosed for more than one to two decades after onset of initial symptoms, resulting in a significant burden of often irreversible neurologic disease. Tools to mitigate under-diagnosis and late diagnosis include greater awareness of the disease among health care providers and access to genetic and (sensitive and specific) biochemical confirmatory testing. It was first proposed >50 years ago that a biochemical diagnosis of CTX could be established through measurement of elevated cholestanol, which has been accepted as the primary biomarker for diagnosis of CTX for decades. Conversely, identification of a normal cholestanol concentration has been considered definitive for exclusion of CTX. Recently, a number of atypical CTX cases with normal plasma cholestanol levels (prior to treatment with CDCA) have been reported. We review here 16 cases of CTX with normal cholestanol. Full biochemical characterization was performed for plasma and urine samples for three cases of atypical CTX, which were demonstrated to possess marked elevations of bile acid pathway intermediates and bile alcohols, which decreased on treatment with CDCA. The reported atypical presentation of CTX demonstrates measurement of plasma cholestanol alone cannot exclude a diagnosis of CTX (it should be noted that treatment with ezetimibe may also decrease baseline cholestanol in patients with CTX). The data presented here demonstrates that bile acid pathway intermediates and bile alcohols are sensitive biomarkers for atypical CTX with normal cholestanol and that such testing is advised, along with CYP27A1 gene analysis, in patients presenting with xanthomas and/or neurologic disease despite normal or near normal cholestanol levels.