The present study begins with an overview of the research about the work of Diogenes Laertius. After stating the modern embarrassment concerning the life and the proper philosophical ideas of Laertius, it continues with the presentation of the discussion on the sources of his work that, although it started back in 19th Century Germany (Quellenuntersuchungen), didn΄t manage to come up with satisfactory conclusions. A summary of the different views is given here together with the portraits of the main writers of the Antiquity that were probably the sources of Laertius (Diodes, Favorinus, Hermippus, Appollodorus, etc.). Richard Goulet tried to introduce an "epistemological rupture" that would solve the sources-problem by pointing to the use of big "documentary blocs" during Laertius΄ composition. There is also the description of Nietzsche΄s contribution to the Laertian problem, not so much because of its philological importance, but with the aim to show how emblematic is the "impurity" and the poetic core of Laertius΄ work for modernism. Next, follows the examination of the question of genres in Laertius, where we distinguish a mixture of different types of ancient historiographies of philosophy such as the Lives (Βίοι), the succession of philosophers (Διαδοχαί), the philosophical expositions (Περί αιρέσεων) and the doxographical surveys. Finally, we see some characteristic valuations of Laertius, notably that of Marcello Gigante who, under the influence of Nietzsche, underlined the importance and the originality of his work not only as doxographical source but as an effort in writing a history of philosophy.