The necessity to distinguish phase C3 of the Roman Period in relation to the cultures inhabiting the territory of present-day Poland has existed for some time now. It was not done by K. Godłowski in his studies on chronology, as he did not yet see the possibility of defining artefacts characteristic for this phase for this phase. He did, however, stipulate that isolating phase C3 would be possible in the future. To date, phase C3 is usually considered together with phase D1, while its separation has long become a fact in the western part of Central European Barbaricum. Somewhat later, the same distinction became possible for southern Scandinavia and the Chernyakhov Culture, as well as for the Masłomęcz Group and, to some extent, for the West Balt Circle in Poland. As of now, there is no basis for isolating phase C3 in the Przeworsk Culture, however, such an attempt, based on new material from the cemeteries excavated in recent decades, can be made for the Wielbark Culture. Comparing the composition of grave assemblages from cemeteries of the Wielbark Culture with materials from the same period from southern Scandinavia, the Elbe Circle, southwestern Germany, and the areas of the Chernyakhov-Sântana de Mureş Culture makes it possible to distinguish a set of characteristic artefacts, consisting of fibulae, belt elements, combs, glass vessels, and several types of beads and pendants. Pottery is not included, as it usually represents local forms on one hand, and its particular types cannot usually be dated within only one phase. The set of artefacts whose peak period of use falls between 310 and 370 AD consists of: Fibulae (Figs. 6, 7): late forms of types A.161 and A.162, i.e. short specimens with a wide bow; types A.169/170, A.172, and A.185; Raupenfibeln; Bügelknopffibeln, especially early forms with a small knob on the head; brooches of type ZG47 with a disc on the bow; brooches with discs (Schildfibeln); A.VI-group brooches of the 2nd series, with a rectangular plate on the foot. Belt buckles (Fig. 8:1–5): types H11–12, H14–16, and H19, i.e. circular, oval, and elongated oval, with a frame of uniform width or slightly thickened; type Keller A. Combs (Fig. 8:8.9): type I: high-backed (or type Kokowski G3) and trapezoidal-backed. Glass vessels (Fig. 8:6.7): types E.223/226, E.237 (type Königsbruch/Ługi), E.230 (type Kowalk/Kowalki). Ornaments (Fig. 9): decorated, usually long, bucket-shaped pendants; axe- and crescent moon-shaped (lunulae) pendants; glass beads of types TM2, 3, 8, 30, 57, 91, 95, 126–134, and 135–149 (spherical: blue, purple, and green; flat-spherical: blue; biconical: blue; segmented: blue and purple; red with a square cross-section; prismatic: particularly blue and purple; oblong cylindrical: blue and red); amber beads of types TM388, 389, 429–430, 465, and 471 (disc-shaped, lathe-turned disc-shaped, figure-of-eight pendants); stone beads of type TM499 (prismatic); beads hung on hoops. Beads, being long-lived forms, are also found in phases C2 and D1, but the ones mentioned above are typical of phase C3. Diagnostic forms of phase D1 are mainly buckles with a heavily thickened frame, lingulate and asymmetrical strap-ends, massive Bügelknopffibeln with a polyhedral knob on the head, and fibulae with a spade-shaped foot (Figs. 10, 11). The seriation table (Table 1) prepared for closed assemblages from the late stage of the Wielbark Culture (phases C2–D1) makes it possible to distinguish three chronological groups corresponding to phases C2, C3, and D1. Due to the small number of assemblages from the two final phases, they do not constitute compact blocks. The group corresponding to phase C2 is clearly defined, with some of its markers, such as the early variants of brooches type A.161 and A.161, three-layer round-backed combs, prismatic glass beads, and figure-of-eight amber pendants, remaining in use during all three phases. The middle group, corresponding to phase C3, is less distinct, however, it can be seen that the artefacts that comprise it precede the introduction of forms typical of phase D1. The most characteristic of phase C2 (group 1) are fibulae A.161 and A.162 of the ‘classical’ form, A.163, A.164, A.168, and A.170, Raupenfibeln, and semicircular buckles of types D17 and D29–31. The buckle with a plate (type Keller A), typical already of phase C3, resides at the border with the next group (C3). Additionally, for phase D1 (group 3) it is necessary to list some other forms represented by very few, or even single, specimens, such as the fibulae of the Peukendorf and Independenţa types, strap-ends of types Madyda-Legutko 11 and 12, and early, i.e. small buckles of the Strzegocice-Tiszáladany-Kercz type. The presented attempt to distinguish phase C3 in the Wielbark Culture may not seem strongly justified yet, but there are many indications that, as more and more assemblages from the end of the Roman Period are discovered, it will be confirmed.