These joint European Association of Neuro-Oncology (EANO)–European Society for Medical Oncology (ESMO) recommendations for the diagnosis and treatment of leptomeningeal metastasis (LM) from solid tumours provide an update of the first joint EANO–ESMO guideline1 and complement the EANO–ESMO guideline on brain metastasis from solid tumours.2 LM is defined as the spread of tumour cells within the leptomeninges and the subarachnoid space. The present recommendations address LM from extra-central nervous system (CNS) solid tumours, but do not address LM from primary brain tumours, lymphoma or leukaemia. The recommendations cover diagnosis, treatment and follow-up, but do not cover the differential diagnosis, treatment-related adverse events (AEs) or supportive or palliative care in detail. The authors propose diagnostic criteria and assign levels of certainty to the diagnosis of LM in order to provide guidance regarding when to treat versus when to intensify diagnostic efforts and which patients to include in clinical trials. The authors also provide a pragmatic treatment algorithm based on LM subtypes. Supporting evidence for this guideline focuses on LM-specific data with reference to the EANO–ESMO guideline on brain metastasis from solid tumours2 when LM-specific data are not available. Given the low level of evidence available, recommendations are often based on expert opinion and consensus rather than on evidence from informative clinical trials. Still, these EANO–ESMO multidisciplinary recommendations serve as a valuable source of information for physicians and other health care providers, as well as for patients and relatives.