MicroRNAs (miRNAs) have a great effect on regulating tumor cell migration, invasion, proliferation and prognosis. However, the mechanism of miR-1236-3p on regulating carcinogenesis is still unknown. In this study, the expression of miR-1236-3p was lower in lung adenocarcinoma tissues than that in adjacent normal tissue. In lung adenocarcinoma A549 cell line, miR-1236-3p decreased ability of cell invasion and migration, furthermore, we show that KLF8 is targeted by miR-1236-3p, and expression of miR-1236-3p is negatively correlated with KLF8. Additionally, miR-1236-3p suppressed the expression of KLF8 and EMT (epithelial mesenchymal transition)-related genes. Overexpression of KLF8 can promote EMT -related genes at protein level. In conclusion, our results support the fact that miR-1236-3p acts as a tumor inhibitor in lung adenocarcinoma by suppressing the activity of KLF8, and it may play a critical role in the diagnosis and treatment of lung cancer. (C) 2017 Published by Elsevier Inc.