The author is dealing with the tile-stamps found in the Roman auxiliary fort at Porolissum attempting to establish which of the many units recorded on tile-stamps stayed in garrison at Porolissum. The author of the present article is arguing his own hypothesis on the subject, based on his own excavations at Porolissum and on all the data gathered from the scientific literature. He finally proposes two tables and a graph that correlate all the information on the troops known from the tile-stamps and stone inscriptions, establishing which of them were in garrison at Porolissum and which were only temporarily attached for building activity. At the same time he sets in chronological order the tile-stamps, demonstrating that the three units which built the headquarters building and the gates of the fort (coh III, L VII GF, L III G) were brought to the Porolissum area late in Hadrian‘s reign, to build in stone the fort and other military facilities in the limes area of Porolissum. The permanent garrison of the fort was composed during the 2nd century AD of two infantry auxiliary units, cohors I Brittonum and cohors V Lingonum, while a third one, numerus Palmyrenorum was probably lodged in a smaller fort situated 500 m away, on the Citera Hill. In the third century, cohors V Lingonum was still there, cohors I Brittonum also for Caracalla‘s time (even not recorded by any later inscription, but, at the same time, not attested in another fort), while the smaller Citera Hill fort was out of use and the numerus Palmyrenorum Porolissensium was moved inside the big fort from Pomet Hill. The author is concluding that the garrison of the military site Porolissum was not changed during the Roman rule in Dacia, all the other tile-stamps found belonging to units brought mainly during the 2nd century to built the military facilities of this strengthened sector of the frontier.