An immunohistochemistry (IH) quality control exercise was conducted as part of the 14th International HLA (human leukocyte antigen) and Immunogenetics Workshop (IHIWS) HLA Expression and Cancer component. Six laboratories participated and the exercises involved performing IH using three monoclonal antibodies (HC-10, β2m and SI00) on three sequential paraffin-embedded melanoma sections provided by one laboratory. High-resolution digital photographs of five IH-stained sections were also distributed for interpretation. While there was generally good agreement between laboratories, several differences in staining and interpretation of IH sections were identified and possible reasons given. Interpretation of the high-resolution digital photographs showed a high level of concordance between laboratories. It is suggested that further exercises are conducted as part of future collaborative activities in order to further characterise areas of variability between IH performance and interpretation of results.