OBJECTIVES: Accurate cost data are required to inform cost-effectiveness assessments of novel treatments in the UK for NICE appraisals. Up to now, levels of resource use to manage CLL and iNHL have mainly been based on clinical expert opinion. However, recently, two key primary care databases in the UK (THIN and CPRD) were linked with Hospital Episode Statistics (HES) at the patient level, thereby providing additional information on secondary care in England. This study aimed to generate more accurate resource use for the management of CLL and iNHL by using the THIN-HES database. METHODS: First, a MEDLINE and UK Health Technology Appraisals (HTAs) reviews were undertaken to identify studies documenting the cost of previously-treated iNHL and CLL in the UK. Then, to collect patients healthcare resource use, THIN database linked to the HES dataset was analysed. RESULTS: Three HTAs were identified as relevant, and cost estimates relied on assumptions from clinical experts. Assumptions varied as TA193 related to relapsed CLL assumed that healthcare visits were three times more frequent post-progression (3 consultations/month: £86) than pre-progression (1 consultation/month: £28.67) while another, TA202, assumed a rather constant number of visits across the two health states (1 clinic visit per month: £121.11). Therefore, analyses of the THIN database linked to HES were undertaken, including more than 1 000 patients. OPCS4 codes and READ codes in the HES and THIN databases respectively, were used to identify treatments prescribed and procedures undertaken. Costs were estimated by applying unit costs from national references. CONCLUSIONS:  To our knowledge, this analysis is the first retrospective observational study to assess the cost of managing previously-treated CLL and iNHL in the UK. This study will serve as an important resource in the health economic evaluation of emerging therapies. This method suggests a greater standardization of disease management costs across HTAs.