Background 4489 Palestinians are political prisoners in Israeli prison facilities (IPS). Incarceration causes physical and emotional strain on the prisoners during and after detention. Little research has been focused on the health effects of imprisonment on Palestinians. The aim in this study was to assess the physical and mental health of long-term detainees in IPS, especially with respect to nutrition and conditions of the facilities. Methods Individuals were selected from a register of 477 ex-detainees released in a prisoner exchange deal on Oct 18, 2011, with convenience sampling—ie, dependent on availability and consent of the person. People who had served less than 8 years in prison or resided outside the West Bank, occupied Palestinian territory, were excluded. 99 prisoners were eligible for the study. Because of budget constraints, only the first ten prisoners, eight men and two women, who consented and were available participated in the study. The participants' testimonies and recollections of events and medical diagnoses were gathered qualitatively with semistructured interviews with a 75-item questionnaire. The questionnaire was reviewed and approved by the Ministry of Detainees and Ex-Detainees, Ramallah, West Bank, which also facilitated the consent of the participants. The questions were modelled on WHO's quality of life 26-item questionnaire and RAND Health's 116-item medical outcomes survey. The focus of the interviews was on post-detention physical health (as assessed at a hospital of the Palestinian Authority), feelings, and a composite account of prison conditions. Interviews were recorded and transcribed. Summary statistics and qualitative analysis were used and responses were analysed thematically. Verbal informed consent was obtained from the participants and recorded. Findings The mean age of the prisoners was 46·9 years (SD 7·9) and imprisonment time was 20·6 years (5·7). Since Feb 26, 2012, five of ten ex-detainees were still receiving treatment for illnesses they contracted during imprisonment. While in prison, four individuals developed peptic ulcers, three had various stomach ailments—colitis, digestive complications, and gallstones; they attributed these problems, diagnosed after release, to nutritional deficiencies. Although some prisoners were diagnosed while in prison after reporting symptoms at clinics for several years, all prisoners confirmed their diagnosis and were treated on release. All respondents had dental problems, with three reporting periodontal disease that was diagnosed by a dentist after release. Eight respondents reported feeling tense, with seven having this feeling regularly within the previous month. Eight individuals felt emotionally stable within the previous month; however, reacclimatisation to societal norms was stressful. All respondents reported that the IPS used the prison clinics to coerce political information from them in exchange for treatment, causing many of the detainees to avoid these clinics except in dire circumstances. Other crucial factors in the prisoners' abstention from clinic attendance were frequent denial of treatment and their distrust of the effectiveness of the medical care provided by the IPS. Individuals who did seek medical treatment had to wait several months and sometimes many years before being permitted to visit a prison hospital and receive treatment. As a consequence, small medical issues became dangerous health complications that required intensive treatment or hospital admission after release from prison. One prisoner was denied treatment for 1·5 years for what he described as serious stomach pain that forced him to be bedridden for days at a time. 1 month after his release, he had a cholecystectomy in a hospital of the Palestinian Authority. His surgeons told him that if he had waited any longer for treatment, his gallbladder would have ruptured. Another prisoner was given incomplete treatment for periodontitis during 10 years. Her ailments became so severe that on release, she had to have several operations. During their interviews, respondents described overcrowding, humidity, pest infestation, and general lack of hygiene as widespread, and felt that poor prison conditions negatively affected their overall health. Interpretation The prison environment exacerbates the physical health problems of detainees. Insufficient nutrition over a long period is the main contributing factor in the types of ailments, particulary dental hygiene and digestive or stomach problems, affecting prisoners. Inadequate provision of health care in Israeli prisons seems to be the cause of poor health in prisoners. Continued follow-up of long-term prisoners is needed to monitor and improve their physical health. Funding None.