The existence of fungi inside the organs of asymptomatic plants has been known since the end of the XIXth century (e.g. Guerin, 1898). However, except for a few sporadic works (e.g. Sampson, 1933), it is not until the end of the XXth century when fungal endophytes began to receive more attention from scientists. An important year in the history of endophyte research is 1977, when Charles Bacon and colleagues found the cause of fescue toxicosis, a syndrome suffered by cattle fed in pastures of the grass Festuca arundinacea (Bacon et al., 1977).