While preparing the materials in Lord Salisbury's library at Hatfield House for microfilming, Miss Caroline Merion discovered a hitherto unknown fragment of a manuscript of Chaucer's Troilus. It was sewed in the spine of the cover (one could hardly call it a binding) of a sixteenth-century rent book containing surveys of some of the property of the Earl of Essex. Probably in the sixteenth century this book came into the hands of the Cecil family, for some of the Essex property mentioned in it was transferred to Lord Burleigh in the 1560's, and in all likelihood this book has been among the Cecil records for over three hundred and fifty years. The fragment of Troilus, which I shall call the Cecil Fragment (CF), is a single page of vellum taken from an unknown manuscript of the poem, and much cut down. It now measures approximately 24½ cm. by 6½ cm., being rather wider at the bottom than the top, since the cutting was rough and irregular. Before being cut down, the manuscript page must have measured something like 28 cm. by 12 to 14 cm. Whoever cut the page apparently cut off strips from the bottom and both sides in order to use only the section in the center of the page. He obviously cared nothing for the writing on the page, for he cut off the beginnings and the ends of the lines of poetry. In spite of him, however, there are large parts of ten stanzas from Book I of Troilus which are still readily legible.