Gaziantep is situated where the Mediterranean region and South East Anatolia region meet. Gaziantep, a city which shares a common border with Syria, has most of its land in the west of South East Anatolia and some part in the east of the Mediterranean region. Gaziantep is surrounded by Birecik and Halfeti towns of Urfa in the east, Besni town of Adiyaman in the northeast, Pazarcik town of Kahramanmaras in the north, Bahce town of Osmaniye in the west, Hassa town of Hatay in the southeast and Kilis province in the south. The lands of Gaziantep take place on the 38 28 and 38 01 east longitudes and 36 38 and 37 32' north latitudes. With 6216 square kms of lands, Gaziantep occupies one percent of Turkey's lands. The altitude of the city center is 850 meters from the sea level but the altitude changes between 250 m and 1250 m, 27 percent of the land is occupied by lowlands.
Mountains can be found in the north from the west of Araban lowland and lie towards the west of the city. These mountains are the extension of the southeastern Taurus Ridge and have very smooth lines. The mountains in the west of the area are natural borders between Gaziantep and Kahramanmaraş-Hatay lowlands. Sof Mountains lie as extension of South East Taurus mountains, and in the south of Sof Mountains lies Gaziantep highland. Dulukbaba mountains lie in the northwest of the city; the peak of these mountains is 1250 m high. Gani Baba and Sarikaya mountains which are parts of Sof mountains in the direction of Hatay are about 1100 meters high. In the west of Gani Baba and Sarikaya mountains Islahiye lowland is situated and lslahiye plateau is situated in the east. Sam Mountains which are 1050 m high are situated between Sof mountains and Dulukbaba mountains. Barak (Doganpinar), Araban, Yavuzeli and Oguzeli lowlands are important lowlands. Euphrates, Nizip , Afrin , Merziman and Alleben streams are important rivers.