Hyperuricemia (HU) and tumour lysis syndrome (TLS) are complications of acute leukaemia and non-Hodgkin lymphoma (NHL) leading to increased morbidity and mortality. The objective of this study was to define incidence and calculate health care cost associated with HU and TLS. 788 acute leukaemia and NHL patients from Belgium, The Netherlands, Spain and UK were screened retrospectively for HU and TLS. Resource use related to HU and TLS was recorded and costs were calculated applying local unit costs. Results showed that HU occurred in 18.9% of patients, and 27.8% of them fulfilled TLS criteria. The cost of HU without TLS was 672 euros (SE 181), the cost of TLS 7,342 euros (SE 1,412). TLS requiring dialysis incurred an average cost of 17,706 euros. In conclusion, it is noted that the observed incidence rates were lower than earlier reports. In addition, some risk factors for HU and TLS (e.g. paediatric patients versus adults) were not associated with increased rates of HU or TLS as a consequence of higher rates of prevention. TLS cases incurred 11 times higher costs than HU cases in which TLS was absent. The main cost drivers in TLS are interventions requiring intensive care.