The Medici-Laurentian Atlas, also known simply as the Medici Atlas (and other variants, e.g. "Laurenziano Gaddiano", "Laurentian Portolano", "Atlante Mediceo" or "Laurentian Atlas"), is an anonymous 14th-century set of maps, probably composed by a Genoese cartographer and explicitly dated 1351, although most historians believe it was composed, or at least retouched, later. The atlas is currently held by the Biblioteca Medicea Laurenziana in Florence, Italy.

The author of the Medici-Laurentian atlas is unknown, save that he comes from the Liguria region of Italy (probably Genoese), and might have composed it for a Florentine owner. The atlas is explicitly dated 1351 (as per its astronomical calendar), but scholars believed it was more likely composed around 1370, possibly from earlier material, and probably amended further later, with emendations as late as 1425–50.

A 1370 date would place it in between the Pizzigani brothers map of 1367 and the Catalan Atlas of 1375, both of which share elements of the Medici-Laurentian map, although it is impossible to tell exactly if it preceded or followed them. It is also contemporaneous with the Libro del Conoscimiento, a fantastical travelogue by an unknown Castilian author, believed to have been written sometime between 1350 and 1399, with which it shares many significant geographic features. The book's author may have inspired, or have been inspired by, the Medici-Laurentian atlas.

The Atlas is currently held by the Biblioteca Medicea Laurenziana in Florence, Italy (Gaddi. Rel. 9).

The Medici-Laurentian atlas is composed of eight sheets. The first sheet is an astronomical calendar, the second sheet contains an unusual world map, the third, fourth and fifth sheets compose a typical 14th-century portolan chart (covering Europe, North Africa, the Mediterranean and Black Seas), the sixth, seventh and eighth sheets are specialized charts of the Aegean Sea, Adriatic Sea and Caspian Sea.

The second sheet, the world map, is the one that has attracted most attention. If the original date 1351 is true, that would make it the first (extant) map to incorporate the travel reports of Marco Polo and Ibn Batuta. It shows Asia up to India, marking places like the Delhi Sultanate and others with reasonable accuracy. The atlas also shows the Caspian as a closed sea (unusual for maps of that time).

Among the most startling features is its depiction of the recognizable shape of the continent of Africa with remarkable precision. Nearly a century before the Portuguese Age of Discovery, the Medici atlas draws the bend of the Gulf of Guinea and shows that Africa has a southern end, i.e. that the Atlantic and Indian Oceans are connected to each other below the African continent.

While the remarkable shape of Africa has given rise to speculative theories about ancient sailing and secret voyages, the explanation is probably more mundane. The probable source of the "Guinea bend" is the legend of the Sinus Aethiopicus, the rumor of a gulf that lay somewhere south of Cape Bojador that was said to penetrate deeply into the African continent. This gulf is described in the fantastical travelogue of the Libro del Conoscimiento (possibly as early as 1350) and finds itself again in the Fra Mauro map (1459), well before it was discovered by Portuguese explorers. The notion that the West African coast did not extend straight south but took a sharp eastward bend, could be a hazy reference to the actual Gulf of Guinea, but more probably it was just a lucky guess and a bit of wishful thinking. (Historian Russell notes that the Portuguese Prince Henry the Navigator was entranced by the legend of the Sinus Aethiopicus, as it held out the prospect of a direct sea route around West Africa to the Christian kingdom of Prester John (Ethiopian Empire), avoiding the complications of travelling through the Muslim lands of Egypt to reach it. In the Medici Atlas, the depth of the penetration of the Sinus indeed almost reaches Ethiopia.)