Mass screening began at 8am on Friday as the north-eastern region hopes to subject 70 percent of the population, or some 350,000 people, to rapid swab tests.
The testing programme was announced ahead of the planned reopening of primary schools and preschools in the area on Tuesday.
The mainly German-speaking province in northern Italy, said infection rates had “reached such proportions” to make testing 350,000 people key to quickly rooting out virus spreaders.
By 10am authorities had tested more than 24,000 people and found 596 positive for Covid-19.
The rapid tests are available on Friday, Saturday and Sunday between 8am-6pm. Testing sites have reportedly been set up at 200 locations, in every municipality. Testing is voluntary and free.
Many of the testing centres have been set up in buildings normally used as polling stations, Italian news agency Ansa reports, and there were long queues forming outside some on Friday morning.
In the city of Bolzano, residents from each street are given 'time windows' during which to participate.
South Tyrol, also known as the autonomous province of Bolzano, is currently classified as a red zone under Italy's regional tier system of coronavirus restrictions.
Regions can implement their own coronavirus restrictions in addition to those set by the government, and every region has its own rules on testing due to Italy's highly decentralisation system.
While Italian authorities maintain that widespread screening of the population is key to controlling the coronvirus outbreak in the country, some experts have cast doubt on the effectiveness of the rapid tests, first used in Italy at airports this summer.