Introduction: Advanced malignant melanoma is a very aggressive disease, historically with poor prognosis before the new advances with immunotherapy and targeted therapies that have changed the standard of care, especially in cutaneous melanoma. Peru has aggressive features such as higher rates of acral lentiginous melanoma (ALM) subtype with historically shorter survival. Methods: This study describes Peruvian patients with advanced melanoma treated with immunotherapy (nivolumab) in two oncological institutions (public and private), including the discussion of the impact on overall survival (OS) divided by subtype (with incidence in ALM histology) and potential biomarkers that could be related to prognosis. Results: We found that immunotherapy is safe, and improves progression-free survival (PFS), OS and objective response rate (ORR) in our patients, with lower benefit in ALM histology. ...