ObjectivesIn recent years, various scientific societies and healthcare organisations have created recommendations aimed at decreasing the use of healthcare interventions that have shown no efficacy or effectiveness. The aim of this study was to assess the impact of an intervention on 12 do-not-do recommendations regarding the laboratory in 7 hospital centres. MethodsBefore-after study conducted in 7 hospital centres of Cordoba and Jaen during 2015 and 2016. Based on the recommendations of existing scientific societies, a consensus was reached on various actions regarding laboratory measurements. We analysed the number and cost of measuring 6 tumour markers (carcinoembryonic antigen, prostate-specific antigen, carbohydrate antigen [CA] 15.3, CA125, CA19.9 and alpha-fetoprotein), thyrotropin, T3, T4, glycated haemoglobin, urea, ferritin and antigliadin antibodies, before and after implementing the consensus. ResultsCompared with the previous year, there were 55,902 fewer laboratory measurements (–19%) in 2016, with an overall savings of €82,100. The reduction in the number of measurements occurred mainly in plasma urea (–50.3%) and in the tumour markers CA125 (–16%), CA19.9 (–11.6%) and CA15.3 (–10.5%). The most pronounced savings were achieved in the measurements of urea (–€21,002), thyroid hormones (–€12,716) and thyrotropin (–€7,638). ConclusionsThe adoption and consensus of do-not-do recommendations among healthcare levels resulted in a significant reduction in unnecessary measurements.