Chimeric antigen receptors (CARs) can be introduced into T-cells redirecting them to target specific tumor antigens. CAR-modified T cells targeting CD19 have shown remarkable activity against CD191 malignancies including B cell acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphomas (NHL). Complete remission rates as high as 90% have been observed for patients with relapsed and refractory ALL and greater than 50% response rates have been seen in heavily pre-treated CLL and NHL. Excitingly, some remissions have been durable without any additional therapy, a finding which correlates with in-vivo T-cell persistence and B-cell aplasia. The major treatment related toxicities include Bcell aplasia, neurologic toxicities, and a potentially severe cytokine release syndrome. This review summarizes outcomes for patients treated with CD19-CAR T-cells while exploring the field's challenges and future directions.