The paper re-examines the traditional view of the relationship between Diogenes of Sinope and Plato. The first part analyses one particular anecdote about Plato’s labeling Diogenes „Socrates who has gone mad“. This narration serves as a starting point of a closer examination of the whole anecdotal tradition of Plato’s encounters with Diogenes. The next part focuses on the Platonic themes of guardians in his Republic and madness in Phaedrus. In the last part of the study it is argued that due to the similarities between Diogenes’ religious beliefs and the opinions of Socrates’ devotees as well as of Socrates himself, Plato’s designating Diogenes with the label of Socratic madness is rather positive than negative.