[Flash mob studies; science in a flash].

The flash mob method is a new way of conducting prospective research whereby relatively simple - but clinically relevant - questions can be answered in a short period of time. The design and intensity of the spirited action - the 'flash' - with which the research is initiated determines the size of the group - the 'mob' - of researchers who will collect research data, and therefore determine the size of the study population. The reach of a flash mob study differs from that of traditional studies and gives flash mob studies a special character. In this article we show how the flash mob method works, the opportunities that it presents, its limitations and the kinds of questions it is able to answer.