Types segmentation categorizes Immunodeficient Mouse Models by genetic and phenotypic characteristics, influencing their suitability for specific research objectives. Severe Combined Immunodeficient (SCID) mice lack functional T and B cells, making them a foundational platform for human cell engraftment, particularly in oncology and immunology studies. NOD‑SCID strains combine SCID mutations with a non‑obese diabetic background, further reducing natural killer (NK) cell activity and enhancing human hematopoietic stem cell engraftment efficiency, which is critical for hematologic malignancy modeling. NSG (NOD‑SCID‑IL2Rγnull) and NOG mice introduce a null mutation in the interleukin‑2 receptor gamma chain, virtually eliminating NK cell function and providing the most permissive environment for xenografts, thereby commanding premium pricing in the market. Rag‑knockout models, deficient in recombination‑activating genes, offer a more targeted immune deficiency, suitable for studies requiring selective T‑cell absence. Each type contributes to the market taxonomy by aligning with distinct application demands, dictating pricing tiers, and shaping the overall market composition.