Recent studies on human NK cells have demonstrated that the NK cell CD94/NKG2 receptors bind to the nonclassical MHC class I molecule HLA‐E. A functional CD94/NKG2 complex has not yet been identified in rodents, but cDNA encoding rat and mouse CD94 and NKG2 have recently been cloned, suggesting that CD94/NKG2 receptors may exist in species other than man. The mouse nonclassical MHC class I molecule Qa‐1 shares several features with HLA‐E. This suggests that Qa‐1 may be similarly recognized by murine NK cells. To study the ability of Qa‐1 to bind to murine NK cells, we have produced a soluble tetrameric form of Qa‐1^b . In the present study, we demonstrate that Qa‐1^b tetramers distinctly bind to a large subset of fresh or IL‐2‐activated NK1.1⁺ /CD3⁻ splenocytes independently of the expression of Ly49 inhibitory receptors. Binding occurs whether NK cells have evolved in an MHC class I‐expressing or in an MHC class I‐deficient environment. Our data suggest the existence of a Qa‐1‐recognizing structure on a large subpopulation of murine NK cells that may be similar to the human CD94/NKG2 heterodimeric complex.