Organ donation after cardiac death (DCD) is increasing markedly, allowing more patients to benefit from transplantation. The time to cardiac death following withdrawal of life-supporting treatment varies widely and is an important determinant of whether organ donation occurs. A prospective multicenter study of potential DCD donors was undertaken to evaluate the time to death and identify associated factors. One hundred and ninety-one potential adult DCD donors at nine UK centers were studied. Treatment withdrawal comprised stopping ventilator support and inotropes. Demographics and physiological variables at the time of death were recorded. Following treatment withdrawal, all potential donors died, with median time to death of 36 min (range 5 min to 3.3 days). Eighty-three potential donors (43.5%) remained alive 1 h after treatment withdrawal, and 69 (36.1%) and 54 (28.3%) at 2 and 4 h, respectively. Univariate analysis revealed that age, cause of death, ventilation mode, inotrope use, systolic blood pressure, FiO2 and arterial pH at treatment withdrawal were all associated with time to death. Multivariable analysis showed that younger age, higher FiO2 and mode of ventilation were independently associated with shorter time to death. This information may aid planning and resourcing of DCD organ recovery and help maximize DCD donor numbers.