The assessment of special categories of non-small-cell lung cancer (NSCLC) patients requires a comprehensive analysis of all factors potentially influencing the daily quality of life and the relative contribution of tumor-related symptoms on the overall patient health status. While for elderly patients prospective evidence and recommendations allow clinicians to better address their patients to a shared treatment, a paucity of reliable data refers to treatment opportunities for these patients, termed frail or unfit, who are not considered eligible for chemotherapy usually administered to adult patients. This consensus was inspired by the absence of clear criteria to define the category of unfit patients in the context of advanced NSCLC in order to share all the available tools for their classification and evaluation and to support decisions for clinical practice on a daily basis. After review of the literature and panelist consensus, a series of items was identified as relevant: age, performance status, renal function, heart failure, previous cerebrovascular events, uncontrolled hypertension, neuropathy, hearing loss, symptomatic brain metastases, severe psychiatric disorders, and absence of caregiver support. On the basis of these factors, a treatment algorithm for clinical practice to categorize unfit NSCLC patient into 3 major clinical scenarios was defined: (1) unfit for cisplatin-based chemotherapy, (2) unfit for carboplatin-based chemotherapy, and (3) unfit for single-agent chemotherapy.