The article considers Thomas Gray’s new approach to English medieval poetry best represented by Chaucer’s works. In his «Observations on English Metre», «Some Remarks on the Poems of John Lydgate», letters, and his Commonplace Book Gray expresses his recognition of high artistic value of medieval poetry; subsequently, a similar approach has been employed by Thomas Warton. Gray’s study of Chaucer has become a lasting contribution to literary criticism as he gained a more profound knowledge of the language and metre of the medieval poets than his contemporaries and predecessors.In his research on metre Gray emphasizes that most critics (G. Puttenham, J. Dryden) didn’t understand Chaucer’s principles of versification and failed to realise that many inequalities in the metre were owing to the neglect of transcribers. Gray’s conclusions on medieval poetry are practically the same as those of the Chaucerians of the XXth century promoting further scientific research, particularly in areas largely unexplored.