Background: In the phase III trial KEYNOTE-189 first-line pembrolizumab (pembro) plus platinum-pemetrexed (pem) significantly improved OS and PFS in metastatic nonsquamous non-small cell lung cancer (NSCLC) without EGFR/ALK alterations. We report outcomes of real-world patients (pts) treated with first line pembro plus platinum-pem in our hospital. Methods: We have done a descriptive, retrospective, single center study developed in a Spanish tertiary hospital where patients with metastatic nonsquamous NSCLC treated with first-line pembro plus platinum-pem have been included. SPSS v23 software has been used to analyze clinical data for OS and PFS using the Kaplan-Meier method. PFS-2, defined as time from first treatment to objective tumor progression on next-line treatment or death from any cause, whichever occurred first, was also recorded using the Kaplan-Meier method. Adverse events (AEs) were graded according to CTCAE v5.0. Results: From December 2019 to May 2022, 79 pts (67.1% M, 26% W; 64y median age, ECOG 0, 1, 2: 5.1%; 88.6% and 6.3%; PD-L1 < 1% 36 [45.6%], PD-L1 1-49% 37 [36.8%], PD-L1 50% 3 [3.8%]; unknown PD-L1 3 [3.8%]; 95% adenocarcinoma) were assessed. After a median follow-up of 19 months, OS was 17 months (5.3-28.7). Stratified by PD-L1 expression, mOS was 9 months (6.3 -11.7) in PD-L1 < 1%; 25 months in PD-L1 1-49%, NR in the rest. Median PFS was 9 months (5.8-12.2). According to PD-L1 expression, mPFS was 6 months (4.6 - 7.4) in PD-L1 < 1%; 19 months (8.7 - 29.2) PD-L1 1-49% and 7 months (0.6 - 13.4) in PD-L1 50%. PFS-2 was 17 months (10.7 - 23.3). At the time of the cut off 66 pts (83.5%) had discontinued treatment: 35 (53%) due to progression, 23 (34.8%) due to toxicity; 2 (3%) due to both, and 6 (9.1%) due to other reasons. Grade 3-5 AEs were observed in 35/79 pts (44.3%). 15.2% pts needed dose-reduction and 32.6% glucocorticoids. Conclusions: First-line treatment with pembro plus platinum-pem has demonstrated benefit in terms of OS, PFS and PFS-2 with tolerable adverse effects. The results obtained in our hospital, taken together, are consistent with those published in KEYNOTE-189 trial. However, the survival of our pts with PD-L1 < 1% seems to be poorer. This finding could be explained by the short median follow-up, low number of patients and differences in baseline demographic characteristics.