For patients with chronic myeloid leukaemia (CML), treatment guidelines recommend monitoring response to treatment with tyrosine kinase inhibitors (TKIs) by testing the BCR-ABL1 fusion gene transcript level using reverse transcriptase quantitative polymerase chain reaction. Despite recent efforts to standardise protocols for BCR-ABL1 testing, some variability remains among laboratories in the UK regarding the techniques used and the approach to reporting results. This increases the risk of misinterpretation of results by both clinicians and patients. An expert panel met to discuss current issues surrounding BCR-ABL1 testing in the UK and to develop guidance for laboratories, with emphasis on the optimal approach to reporting laboratory results. Topics included the minimum required information to include in the laboratory report, units of measurement, test sensitivity and BCR-ABL1 transcript variants. To aid communication between laboratories and clinics, standard forms were generated that could be used by (i) clinics when submitting samples to laboratories, and (ii) laboratories when reporting results to clinics. Standardising the way in which BCR-ABL1 test results are reported from laboratories to clinics should help to improve communication, interpretation of results and patient care.