Aims and method: A retrospective case-note review was undertaken at five English prisons between June 2008 and March 2009 to estimate the proportion of psychiatric medicines (antidepressants, antipsychotics and hypnotics/ anxiolytics) reported at prison reception that are discontinued on entry to prison. Results: Of the 1006 records sampled, the review showed that 18% of prisoners had been prescribed psychiatric medication before being placed in custody. Altogether, 240 separate psychiatric medicines were recorded among prisoners at reception. Of these, 47% were not prescribed during the first week of custody. In only 11% of cases where medication was discontinued had psychiatric assessment been completed. Clinical implications: Prison mental health policy states that psychiatric medication should not be withdrawn in custody without proper clinical assessment. Denial of medication in the absence of clinical assessment during early custody has the potential to create additional stress in individuals during a period of increased vulnerability and risk. Declaration of interest: None.