Former prisoners are a vulnerable population, and suicide rates among this group are high, particularly following release from prison.

To explore former prisoners’ engagement with mental health services before death by suicide, and to examine the demographics, clinical history and clinical care of this patient group and compare them with patients who died by suicide who had not been to prison.

The clinical, sociodemographic and care characteristics of patients in contact with mental health services who died by suicide in the UK were examined in a national clinical survey between 1 January 2001 and 31 December 2021, and comparisons were made between former prisoners and patients with no history of being in prison.

Of the 33 381 (median age 46 years, range 10–100; 65.6% male) patients who died by suicide in the UK and had been in contact with mental health services in the 12 months before death, 3335 (11%) were ex-prisoners (male n = 2988, 90%; female n = 347, 10%). Compared with other patients, ex-prisoner patients had higher frequencies of personality disorder, schizophrenia and delusional disorders, as well as childhood abuse. Ex-prisoner patients were more likely to be male, to be aged between 45 and 65 years (median age 39, range 17–89), to live in deprived areas and to have a history of substance misuse. We found no differences in ethnicity.

Mental health services need to focus particularly on patients with a history of being in prison who are experiencing economic adversity and offer substance-use-related interventions to ensure continued patient engagement. The link with deprivation is striking at a time at which rising costs of living are resulting in more health inequalities.