MNS血型系统（英文：MNS antigen system），亦称MNS抗原系统或MNSs血型系统，是人类血型系统之一。其编码基因位于4号染色体上。MNS血型系统包括超过40种抗原，其中四种最为重要，分别称为M、N、S、s抗原，它们对应的抗体都与输血反应有关。

M、N、S、s抗原均为糖蛋白，与MN有关的糖蛋白称为血型糖蛋白A（glycophorins A，GPA），与Ss有关的称为血型糖蛋白B（glycophorins B，GPB）。

The MNS antigen system is a human blood group system based upon two genes (glycophorin A and glycophorin B) on chromosome 4. There are currently 46 antigens in the system, but the five most important are called M, N, S, s, and U.

The system can be thought of as two separate groups: the M and N antigens are at one location on the ECM and S, s, and U are on a closely related location. The two groups are very closely located together on chromosome 4 and are inherited as a haplotype.