Mean Hb values for each stage of ROP in our study group are as follows: stage 1 (10.41 ± 4.88 g/dl), stage 2 (10.56 ± 4.16 g/dl), stage 3 (9.47 ± 3.43 g/dl), stage 4 (9.3 ± 0.848 g/dl), and matured retina (12.15 ± 4.83 g/dl). This evidence concerns the gene GSTM1 and retinopathy of prematurity.