OBJECTIVE: To study the kidney development of fetuses with intrauterine growth restriction and related mechanism. STUDY DESIGN: Twenty-three kidney samples of dead fetuses from legally induced abortion and stillborn fetuses in our hospital between September 2012 and September 2015, including 11 samples with fetal growth restriction (FGR) and 12 non-FGR samples, were collected and referred to as FGR group and control group, respectively. The fetal weight, kidney weight, and kidney volume were measured by an electronic scale using the liquid substitution method. The number of nephrons was determined using the acidification method. The apoptosis of kidney cells was detected by the TUNEL assay and flow cytometry. The expressions of anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax were detected by the immunohistochemical method and Western blot. RESULTS: The weights of fetus and kidney, kidney volume, and nephron number of the FGR group were significantly lower than those of the control group (p= 0.021, 0.007, 0.019, 0.025). Compared with the control group, the number of apoptotic cells and the expression of Bax protein in the FGR group were significantly higher, but the expression of Bcl-2 protein was significantly lower (p=0.011, 0.009). CONCLUSION: Intrauterine growth restriction and poor environment promoted a decrease in the number of nephrons and accelerated kidney cell apoptosis. Meanwhile, the expression of pro-apoptotic protein Bax increased, but that of anti-apoptotic protein Bcl-2 decreased. © Science Printers and Publishers, Inc.