A pandemic of loneliness is hitting the aging population. As COVID19 forced us to isolate ourselves, we are in a better position to understand consequences of social distancing. The recent literature showed that older incarcerated adults are particularly at risk of health-related complications due to isolation in the prison environment, reducing their social capital. Mental and physical health can be severely affected by loneliness and social isolation, especially in prison.; Our qualitative study investigates the view of older persons deprieved of their liberty on loneliness and social isolation pertaining to their mental health. We interviewed 57 older participants, including imprisoned individuals and forensic patients, following a semi-structured interview guide. During the data management and data analysis process, we excluded 7 interviews which were of poorer quality. Thereafter, we analyzed the remainders following a thematic approach.; Most interviewees experience loneliness following lack of significant human relationships in prison. Making friends appears to be a challenge for all the participants, because, for one thing, they do not find people with similar interests. Also, secure institution setting aggravates isolation due to the restrictions of movement placed such as rules concerning movement between floors, hindering intimate relationship, and separation between friends. Moreover, contact with prison personnel is limited and lack social capital (e.g. trust).; To our knowledge, this study is one of the first to present incarcerated persons' perspective on loneliness, social isolation and poor social capital in the Swiss prison setting. These has been reported to cause health problems both somatic and psychological. Our participants experience these deleterious factors in detention. As prisons have the possibility to become a health-promoting environment through connectedness, friendship, and trust promotion, stakeholders need to better their social capital.