This is an English translation of Freud's report of a lecture that he delivered in 1895 on the 'Mechanism of obsessional ideas and phobias'. The report was not included in the Standard Edition of Freud's psychological works, and nor was it included in any of the other collections of his writings. The lecture described in this report seems to have been derived directly from Freud's contemporaneous essay on 'Obsessions and phobias' (1895b). However there are a few discrepancies between the two, and these are discussed in the footnotes to the translation.