To address antigen escape and loss of T-cell functionality, we report a phase-1 clinical trial (NCT04007029) evaluating autologous naive and memory T (TN/MEM) cells engineered to express a bispecific anti-CD19/CD20 CAR (CART19/20) for patients with relapsed/refractory NHL, with safety as the primary end point. Ten patients were treated with 36–165 x 106 CART19/20 cells. No patient experienced neurotoxicity of any grade, or over grade-1 cytokine release syndrome. One case of dose-limiting toxicity (persistent cytopenia) was observed. Nine of ten patients achieved objective response (90% ORR), with seven achieving complete remission (70% CR rate). One patient relapsed after 18 months in CR, but returned to CR after receiving a second dose of CART19/20 cells. Median progression-free survival and overall survival were not reached with a 17-month median follow-up. In conclusion, CART19/20 TN/MEM cells are safe and effective in patients with relapsed/refractory NHL, with durable responses achieved at low dosage levels.