In 1985 the first of four research seasons at site 4 at Tomasze, comm. Czerwin, distr. Ostrołęka, woj. mazowieckie, produced a nearly complete unique pin of copper alloy (Fig. 1a). It belongs to a large and morphologically mixed group of pins, which are tied in their origins with the area of Jastorf Culture. In relative chronology these forms belong in phases Lt B2 and Lt C1. Further finds of Holstein pins in Poland are known from Żółwin, distr. Międzyrzecz, Sobiejuchy, distr. Żnin, and Łuszczewo, distr. Konin (Fig. 1b–d). Previously they were dated to the Early Pre-Roman Period and considered Jastorf imports in Pomeranian Culture. Still, their connection to the latter culture unit is rather doubtful considering that none of these forms were discovered in context with Pomeranian Culture finds. New evidence from rescue excavations associated with construction in the last decade or so of the gas pipeline and motorways suggests the presence in the Polish Lowland between the Odra and the Vistula of a previously unknown Jastorf group, different from the Oder and the Gubin Groups. Most probably, the pin finds from Żółwin, Sobiejuchy and Łuszczewo would be associated with this group. In terms of chronology they represent later forms of Holstein pins, datable to phase Lt C1. A similar dating may be adopted for the pin from Tomasze, but the question of its culture attribution is slightly different. Jastorf finds to the east of the Vistula are not as common as in the area west of that river and have a less narrow dating. At the same time, it is worth recalling that the late phase Lt C1 was the time of the emergence of Przeworsk Culture, its presence in north Mazowsze indicated by a small body of finds of early date. At the present stage of research it the pin from Tomasze probably may be considered a stray find of Jastorf Culture in the area east of the Vistula and dated to a period slightly predating or contemporary with the emergence of Przeworsk Culture.