Tolna, megye (county), south-central Hungary. It lies in the southern part of Transdanubia and borders the counties of Fejér to the north, Bács-Kiskun to the east, Baranya to the south, and Somogy to the west. Szekszárd has been the county seat since 1779. Other important towns include Bonyhád, Tolna, Paks, Simontornya, Dombóvár, and Tamási.
The landscape is flat in the eastern territories occupied by the Mezoföld (a loess tableland) and the riverine lowlands that meet the Danube River on the county’s eastern border. It rises gently in the west, in the Kapos-Koppány hills and the Tolna highlands, and in the southern outliers of the Mecsek Mountains. Its rivers—the Kapos, Koppány, Sárvíz, Lajvér, and Donáét—flow into the Danube via the Sió River.
There are no mineral resources in Tolna, but the county is rich in fertile soils. Its economy is agriculture-based: grains, sunflowers, and fodder plants are the major crops. Cattle and pigs are raised. Viticulture in the Szekszárd area has been a tradition for nearly 2,000 years.
Industry in Tolna was underdeveloped until the 1960s, but the planned industrialization of the 1970s led Budapest-based companies to open branches in the county’s cities and towns. Starting in the mid-1970s, several large state investments took place—the most significant of which was the nuclear power plant in Paks, which opened in 1976, had four reactors by the mid-1980s, and remains Hungary’s only nuclear power facility. The Dunaföldvár bridge (built 1928–32) is the only bridge over the Budapest-Baja section of the Danube and is of great importance. A huge biorefinery in Dunaföldvár uses feed-grade corn to produce animal feed, bioethanol, and corn oil. The enamelware produced in Bonyhád is known worldwide.
Tourist attractions include the Gemenc Forest (part of Duna-Dráva National Park), the game reserve at Gyulaj (famous for its fallow deer), the Sárköz region (known for its peasant costumes and folk arts), the Simontornya fortress, and the spas at Tamásfürdo and Dombóvár.
Tolna was founded by Stephen I, and its borders have hardly changed since then. During the Ottoman Turkish domination of the region in the 16th century, its population dispersed and the county became sparsely inhabited. Resettlement commenced in the 1720s. There were large numbers of Germans among the settlers. Area 1,430 square miles (3,703 square km). Pop. (2011) 11,126; (2017 est.) 10,997.