Objective: To investigate the perception of self-isolation at home in patients with cancer during the lockdown period because of the COVID-19 outbreak in Italy.Methods: A cross-sectional descriptive study was conducted through an online survey from March 29th to May 3rd, 2020. Perception of self-isolation was assessed in patients with cancer during quarantine at home using the ISOLA scale, after evaluation of its psychometric properties. Content analysis was used to analyse two open-ended questions.Results: Participants were 195 adult patients with cancer (female = 76%; mean age = 50.3 ± 11.2; haematological malignancy = 51.3%). They reported moderate isolation-related suffering (M = 2.64 ± 0.81), problems in the relationship with others (M = 3.31 ± 1.13), and difficulties in the relationship with oneself (M = 3.14 ± 1.06). Patients who experienced significantly more social problems were the older ones, with lower education, and living without minor children. Overall, four main categories emerged from the qualitative content analysis: 1) Lack of freedom and social life, 2) Uncertainty and worries, 3) Feeling supported, and 4) Dealing with isolation.Conclusion: Living with cancer in the COVID-19 pandemic was often perceived as an isolating experience, primarily in terms of detachment from loved ones.