Achilles Tatius' romance is a history of the adventures of two lovers, Cleitophon and Leucippe. It bears the title , and consists of eight books. Notwithstanding all its defects, it is one of the best love-stories of the Greeks. Cleitophon is represented in it relating to a friend the whole course of the events from beginning to end, a plan which renders the story rather tedious, and makes the narrator appear affected and insipid. Achilles, like his predecessor Heliodorus, disdained having recourse to what is marvellous and improbable in itself, but the accumulation of adventures and of physical as well as moral difficulties, which the lovers have to overcome, before they are happily united, is too great and renders the story improbable, though their arrangement and succession are skilfully managed by the author. Numerous parts of the work however are written without taste and judgment, and do not appear connected with the story by any internal necessity. Besides these, the work has a great many digressions, which, although interesting in themselves and containing curious information, interrupt and impede the progress of the narrative. The work is full of imitations of other writers from the time of Plato to that of Achilles himself, and while he thus trusts to his books and his learning, he appears ignorant of human nature and the affairs of real life. The laws of decency and morality are not always paid due regard to, a defect which is even noticed by Photius. The style of the work, on which the author seems to have bestowed his principal care, is thoroughly rhetorical: there is a perpetual striving after elegance and beauty, after images, puns, and antitheses. These things, however, were just what the age of Achilles required, and that his novel was much read, is attested by the number of MSS. still extant.

Suidas ascribes to this same Achilles Tatius, a work on the sphere (περὶ σφαίρας), a fragment of which professing to be an introduction to the Phaenomena of Aratus (Εἰσαγωγὴ εἰς τὰ Ἀράτου Φαινόμενα) is still extant. But as this work is referred to by Firmicus (Mathes. 4.10), who lived earlier than the time we have assigned to Achilles, the author of the work on the Sphere must have lived before the time of the writer of the romance. The work itself is of no particular value. It is printed in Petavius, Uranologia, Paris, 1630, and Amsterdam, 1703, fol.

Suidas also mentions a work of Achilles Tatius on Etymology, and another entitled Miscellaneous Histories; as both are lost, it is impossible to determine which Achilles was their author.