Sclerites of machaeridians (Annelida) and polyplacophorans (Mollusca) from the UpperOrdovician (Katian–Hirnantian) Boda Limestone of the Siljan district, central Sweden are described forthe first time. Four taxa of machaeridians were found, but with one exception they are either known froma single isolated sclerite or only one type of sclerite. The largest taxon is represented by an inner modifiedsclerite of Plumulites sp. A from Osmundsberget Quarry. The complete scleritome is estimated to havereached a length of 12–15 cm. A more diverse material allows the description of Plumulites eueides sp.nov. from Kallholn Quarry. Within smaller cavities in Solberga Quarry minute sclerites of two taxa werefound; Lepidocoleus sp., and Turrilepas sp. The latter record represents the third known Ordovicianoccurrence and the youngest from that period. Association with minute blind trilobites andconcentrations of tiny articulated ostracodes suggest that these small cavities represented cryptichabitats. Two polyplacophoran sclerites are also described: one intermediate sclerite of Chelodes sp. Afrom Jutja¨rn Quarry, with only the outer surface exposed, and one intermediate sclerite of Spicuchelodes?sp. from Kallholn Quarry, with only the inner surface exposed. These represent rare examples ofOrdovician chitons recorded from outside Laurentian terranes.