Curcumin is a dietary polyphenol from turmeric with numerous pharmacological activities. Novel animal and human studies indicate that curcumin can affect different immune cells, such as various T lymphocyte subsets, macrophages, dendritic cells, B lymphocytes and natural killer cells, which results in decreasing severity of various diseases with immunological etiology. The present review provides a comprehensive overview of the effects of curcumin on different immune cells and immune system‐related diseases. The present review provides a comprehensive overview of the effects of curcumin on different immune cells and immune system‐related diseases.