Münchausen syndrome is a disorder defined by the following: acute factitious symptoms leading to inappropriate investigation and therapy, a restless journey from hospital to hospital and autobiographical falsification. We report here a 20-year-old woman who presented at our hospital consultation of internal medicine with laboratory-test results suggesting the diagnosis of leukemia. A new complete blood cells count and a medullogram by sternal puncture did not show any abnormality. Comparative examination of laboratory-test sheets lead to the diagnosis of Münchausen syndrome as some results had been falsified. With unlimited access to information through internet and word or image processing softwares, laboratory results have become easy to falsify nowadays, particularly for patients with Münchausen syndrome, who may then be quite difficult to diagnose accurately in the context of medical consultation.