Prognostication was a key tool of the physician in the pre-modern period: a time when diagnosis was difficult, treatment often ineffective and surgery a dangerous last resort. This paper will survey the wide range of prognosticatory methods available to the learned physician and demonstrate that the methods used were open to interpretation and therefore to manipulation and ambiguity. It will argue that ambiguous prognostics were useful to the late medieval medical practitioner as he strove to care for both the body and the soul of patients approaching death.