Wilson's disease (WD) is a rare autosomal recessive condition with protean clinical manifestations that results from biallelic ATP7B mutations. However, non-destructive tissue tests to be applied clinically to tissue specimens are not widely available to effectively assess patients for possible WD. Previously, we showed that metallothionein (MTH) immunohistochemistry has a high sensitivity and specificity for WD diagnosis and, thus, represents a potentially powerful diagnostic tool that can be used in routine histologic sections. We sought to validate this finding in a large cohort of bona fide WD patients and to correlate metallothionein expression with other histologic features. We identified 91 cases of WD, which included 28 needle biopsies and 64 explants from 14 centers worldwide. Histologic features were evaluated, and a histopathological pattern was assigned to each case. All cases were evaluated with Masson trichrome and MTH immunohistochemistry (clone UC1MT, Abcam) using previously published technique. Liver tissues from chronic cholestatic diseases (n= 42) were used as controls. The median age of the cohort was 28.5 years. Out of 91 total cases, 83 were positive for MTH immunostain. In the controls, all 42 cases were negative for MTH immunostain. The sensitivity and specificity of MTH immunostain for WD were 91.20% and 100%, respectively. MTH immunohistochemistry is a highly sensitive and specific cost-effective screening tool for WD. It can be used for patients across age groups, varied histologic patterns, and fibrosis stages. This marker could prove to be a valuable tool in the evaluation of patients with possible WD.