Iron nails with different shapes and sizes were excavated from Hadrianoupolis in southwestern Paphlagonia located 3 km west of Eskipazar, the modern town near Karabük. Possible microstructural formations of iron based nails produced in Roman and Early Byzantine Period were examined in this study. Throughout the study chemical compositions of these iron based nails reflecting different microstructures were measured. According to our experimental results, we concluded that they were made of low carbon iron generally containing a number of non-metallic features indicating surface carburization and widmanstaetten formations. The effect of P, As and Ni amounts in iron alloy was observed from chosen nails. These results revealed that the nails were produced by an iron technology based primarily on the bloomery technique completed by smith process based on hammering. Various microstructures were observed according to the production processes of the nail. K e y w o r d s : bloomery, smithing, iron nail, Early Byzantium, archaeometallurgy