Celiac disease (CeD) is an autoimmune disorder in which ingestion of dietary gluten triggers an immune reaction in the small intestine. The CeD lesion is characterized by crypt hyperplasia, villous atrophy and chronic inflammation with accumulation of leukocytes both in the lamina propria (LP) and in the epithelium, which eventually leads to destruction of the intestinal epithelium and subsequent digestive complications and higher risk of non-hodgkin lymphoma. A lifetime gluten-free diet is currently the only available treatment. Gluten-specific LP CD4 T cells and cytotoxic intraepithelial CD8+ T cells are thought to be central in disease pathology, however, CeD is a complex immune-mediated disorder and to date the findings are mostly based on analysis of heterogeneous cell populations and on animal models. Here, we comprehensively explore the cellular heterogeneity of CD45+ immune cells in human small intestine using index-sorting single-cell RNA-sequencing. We find that myeloid and mast cell transcriptomes are reshaped in CeD. We observe extensive changes in the proportion and transcriptomes of CD4+ and CD8+ T cells and define a CD3zeta expressing NK-T-like cell population present in the control LP and epithelial layers that is absent and replaced in CeD. Our findings show that the immune landscape is dramatically changed in active CeD which provide new insights and considerably extend the current knowledge of CeD immunopathology.