Mendelian randomization analysis using large-scale epidemiological and genetic data is being used as a technique to figure out causal effects between complex exposure (e.g., risk factors and comorbid diseases) and a disease of interest beyond the fundamental limitations of existing observational studies. Mendelian randomization analysis is conducted using genotype data as an instrument variable that reflects exposure factors to evaluate the causal effects. Since these genetic instrument variables are determined during the process of fertilization, causal effects can be assessed by avoiding bias caused by confounding factors or reverse causality, which is commonly observed in observational studies. Many Mendelian randomization studies have been published in the area of cardiovascular disease or cancer research, and various epidemiological factors as exposure variables have also been analyzed to reveal their causal effects on various diseases. As the CKDGen data were released recently, Mendelian randomization studies are being conducted in the field of nephrology. We have conducted Mendelian randomization studies regarding the causal effects of various exposure, including education, diet, mental health, lifestyle, comorbid diseases, or biomarkers, which were suggested in observational studies but were difficult to prove their causality to CKD or GFR. Through these findings, we would like to help clinicians better understand factors that have a causal effect on kidney function and suggest exposure factors to be corrected to mitigate kidney function deterioration.