This study aimed to identify the earliest predictive time window for tacrolimus IPV and to evaluate its association with <i>de novo</i> donor-specific antibody (dnDSA) development and rejection, while also examining the impact of CYP3A5*3 and CYP3A4*1G polymorphisms on IPV.<h4>Methods</h4>In a single-center retrospective study (2016-2021) of Chinese kidney transplant recipients, tacrolimus IPV (coefficient of variation) was calculated across consecutive intervals from transplantation to month 24, using all available whole blood drug trough concentration measurements within each window. Here, CYP3A4 is linked to kidney transplant.