Little is known about the general healthcare needs of detainees in police custody. The aims of this study were to: determine the level of general health issues, diseases and/or pathology for detainees in police custody, and to determine how well those general health issues, diseases and/or pathology are being managed. This was done by a detailed analysis of healthcare issues of a cohort of detainees and reviewing intended and prescribed medication needs with current medication availability. In August 2007, a prospective detailed, anonymised, structured questionnaire survey was undertaken of 201 detainees in police custody in London, UK. Of these 83.6% consented to participate in the study. 85.1% of subjects were male; mean age was 33.9 years; 70.8% had English as a first language; 13.7% were of no fixed abode; 70.2% were registered with a general practitioner (primary care physician); 25% were already in contact with other healthcare teams; 7.1% had previously been sectioned under the Mental Health Act 1983; 16.7% had previously intentionally self-injured; 33.9% were dependent on heroin, 33.9% on crack cocaine; 25% on alcohol, 16.6% on benzodiazepines and 63.1% on cigarettes. 56% of subjects had active medical conditions; of those with active medical conditions 74% were prescribed medication for those medical conditions; only 3/70 had their medication available. 28/70 were not taking medication regularly, and many were not taking it at all. Three subjects who had deep vein thromboses were not taking their prescribed anticoagulants and six subjects with severe mental health issues were not taking their anti-psychotic medication. Mental health issues and depression predominated, but there was a very large range of mixed diseases and pathology. Asthma, epilepsy, diabetes, deep vein thrombosis, pulmonary embolism, hepatitis, and hypertension were all represented. The study has achieved its aims and has also shown that – in part because of the chaotic lifestyle of many detainees – appropriate care was not being rendered, thereby, putting both detainee, and potentially others coming into contact with them, at risk.