This is the author accepted manuscript. The final version is available from BMJ Publishing Group via the DOI in this record.The data analysed within this project are administrative data; the Prescribing Information System (PIS) and the Scottish Morbidity Record – 01 Inpatient (SMR01). Anyone wishing to access the data should apply to the electronic Data Research and Innovation Service (eDRIS): www.isdscotland.org/Products-and-Services/EDRIS/index.asp?Co=Y. Applications to access the data will need to be approved by the Public Benefit and Privacy Panel for Health and Social Care (PBPP): www.informationgovernance.scot.nhs.uk/pbpphsc/. Instructions and guidance on how to apply to access the data can be found here: www.informationgovernance.scot.nhs.uk/pbpphsc/home/for-applicants/.Objectives: To identify whether the abolition of prescription fees in Scotland resulted in: a) increase in the number (cost to NHS) of medicines prescribed for which there had been a fee (inhaled corticosteroids); b) reduction in hospital admissions for conditions related to those medications for which there had been a fee (asthma or Chronic Obstructive Pulmonary Disease (COPD)) – when both are compared to prescribed medicines and admissions for a condition (diabetes mellitus) for which prescriptions were historically free. Design: Natural experimental retrospective General Practice level interrupted time series (ITS) analysis using administrative data Setting: General Practices, Scotland, United Kingdom Participants: 732 (73.6%) General Practices across Scotland with valid dispensed medicines and hospital admissions data during the study period (July 2005 – December 2013) Intervention: Reduction in fees per dispensed item from April 2008 leading to the abolition of the fee in April 2011, resulting in universal free prescriptions Primary and secondary outcome: Hospital admissions recorded in the Scottish Morbidity Record – 01 Inpatient (SMR01) and dispensed medicines recorded in the Prescriptions Information System (PIS). Results: The ITS analysis identified marked step reductions in adult (19-59 years) admissions related to asthma or COPD (the intervention group), compared to older or young people with the same conditions or adults with diabetes mellitus (the counterfactual groups). The prescriptions findings were less coherent and subsequent sensitivity analyses found that both the admissions and prescriptions data were highly variable above the annual or seasonal level, limiting the ability to interpret the findings of the ITS analysis. Conclusions: This study did not find sufficient evidence that universal free prescriptions was a demonstrably effective or ineffective policy, in terms of reducing hospital admissions or reducing socioeconomic inequality in hospital admissions, in the context of a universal, publicly administered medical care system, the National Health Service of Scotland.This work was funded by the Farr Institute @ Scotland, which is funded by the following consortium: Arthritis Research UK, the British Heart Foundation, Cancer Research UK, the Economic and Social Research Council, the Engineering and Physical Sciences Research Council, the Medical Research Council, the National Institute of Health Research, the National Institute for Social Care and Health Research (Welsh Assembly Government), the Chief Scientist Office (Scottish Government Health Directorates), (MRC Grant No: MR/K007017/1). JF and AJW worked for the Scottish Collaboration for Public Health Research and Policy which is funded by the SCPHRP core grant from the Medical Research Council (Grant Number MR/K023209/1) and the Chief Scientist Office of Scotland. WH received support from the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care (CLAHRC) for the South West Peninsula.