Bromazolam is a new psychoactive substance (NPS) benzodiazepine commonly identified by drug checking services and in post-mortem toxicological analyses in the United Kingdom, Europe, and North America. At the time of writing, there are no studies that present quantitative analyses of bromazolam in street tablets. Here we describe the first quantitative analysis of bromazolam tablets, from samples submitted by UK drug checking services and police forces between 2022 and 2025. Using validated GC-EI-MS and H NMR methods, 47 tablet samples were quantified revealing a median bromazolam dose of 0.49 mg (interquartile range = 1.02 mg) per tablet, range of 0.09-5.4 mg. Over half of the tablet submissions (55%) mimicked the appearance of licensed pharmaceuticals alprazolam or diazepam, raising significant concerns around mis-selling of street bromazolam tablets and the risks of unintentional high-dose exposure to an NPS compound. To contextualise these findings, we also report post-mortem data from the UK National Programme on Substance Use Mortality (NPSUM), in which bromazolam was detected in 396 drug-related deaths between April 2021 and July 2024. Bromazolam detections in deaths rose from 28 deaths in 2021 to 160 deaths in 2023. Bromazolam was implicated in causing death in 82.8% of cases, with a median post-mortem blood concentration of 43 ng/mL. Notably, bromazolam was co-detected with an average of seven other substances per case, most commonly other central nervous system (CNS) depressants. These findings underscore the public health risks posed by bromazolam as an NPS benzodiazepine and highlight the urgent need for monitoring, harm reduction and forensic toxicology guidance.