Kayi Dineja, Arabic: منطقة كايس, romanized: minṭaqa Kāyas) is one of ten first level national subdivisions in Mali called Regions.

The Falls of Félou (15 km from Kayes), the Falls of Gouina (60 km to the south-east of Kayes on the Sénégal River), Talari Gorges, Lake Magui and Lake Doro are located in the region.

The largest cities in the region are Kayes, Kita, Bafoulabé, Nioro du Sahel, Diéma, Yélimané, Diangounté, Sadiola, and Kéniéba The Bafing National Park and the Boucle du Baoulé National Park are located in the region.

In 1855, Louis Faidherbe, Governor of Senegal, built a fort at Medina which would be besieged by El Hadj Omar Tall, in an 1857 war against the sovereign of Khasso.

Essential at the time, the railroad had an important place in the lives of the inhabitants, as described in Ousmane Sembène's novel God's Bits of Wood.