In this paper, the impact of hot carrier stress on the mismatch properties of n and p metal–oxide–semiconductor (MOS) field-effect transistors (FETs) with different sizes produced using 0.15 µm complementary MOS (CMOS) technology is presented for the first time. The research reveals that hot-carrier injection (HCI) does degrade the matching properties of MOSFETs. The degree of degradation closely depends on the strength of the HC effect. Thus, it is found that, under the stress condition of drain avalanche hot carrier (DAHC), the properties of nMOSFETs rapidly and greatly become worse, but the changes are small for pMOSFETs. For analog circuit parameters, it is found that the after-stress lines of n and pMOSFETs exhibit a cross point in σ (ΔVt,op) drawings. It is suggested that the cross point can be used to indicate the minimal size in order for n and p pairs to have the same degree of ΔVt,op mismatch in designing analog circuits. In addition, interpretations for the differences between n and pMOSFETs and between ΔVt,op and Ids,op mismatches are provided with experimental verifications.