In this article, we present data on endothelial Nitric Oxide Synthase (eNOS) gene T786C and G894T polymorphisms in Greek steady-state Sickle Cell Disease patients in comparison to healthy controls. Moreover, eNOS mRNA levels were determined in peripheral blood samples from 18 patients and 9 controls. This article complements our recently published article named “Prognostic value of eNOS T786C and G894T polymorphisms in Sickle Cell Disease” (I. Armenis, V. Kalotychou, R. Tzanetea, Z. Kontogeorgiou, D. Anastasopoulou, M. Mantzourani, M. Samarkos, K. Pantos, K. Konstantopoulos, I. Rombos, 2016) [1].