Background This survey of tortoise owners was performed to investigate the factors contributing to morbidity and mortality during and post‐brumation in captive Testudo species in the United Kingdom. Methods Information regarding a total of 270 tortoises was included in the study, from 252 completed surveys. Binary logistic regression and multivariate modelling were used to evaluate the potential predictors associated with brumation mortality and those associated with post‐brumation problems. Results A 7.78% mortality rate was found, with 7.22% of surviving tortoises reported to have post‐brumation health concerns. Brumation in a garden and an uncontrolled reduction of temperature prior to brumation were the main risk factors for morbidity and mortality in the study. Conclusions Veterinarians should be aware of these risk factors to ensure they target husbandry and brumation advice to owners of tortoises to reduce these risks.