Aim: To evaluate treatment results in advanced/metastatic melanoma patients treated with anti-PD-1 immunotherapy in routine practice in oncology centers in Poland. Methods: Multicenter retrospective analysis included 499 patients with unresectable/metastatic (stage IIIC–IV) melanoma treated with anti-PD-1 in first-line therapy. Results: Estimated median overall survival (OS) and progression-free survival (PFS) were 19.9 and 7.9 months, respectively. Multivariate analysis confirmed that ECOG 0, no brain metastases, normal lactate dehydrogenase level and occurrence of immune-related adverse events (irAEs) were statistically significantly associated with improved OS and PFS. Any irAE occurred in 24% of patients. Grade 3 or Grade 4 irAEs occurred in 6% of patients. Conclusion: Analysis revealed a slightly worse OS in real-world treatment in comparison to clinical trials (KEYNOTE-006 and CheckMate 066). Polish population treatment results are similar to other studies of real-world data. PFS and ORR are similar in our research and clinical trials.