In view of the key role of eNOS in vasculo- and angiogenesis and the association of eNOS polymorphisms with diabetic retinopathy, we investigated the association between eNOS T−786C and eNOS 27-bp repeat (b/a) functional polymorphisms and the development of severe ROP in low birth weight infants (LBW). The gene discussed is NOS3; the disease is diabetic retinopathy.