ENIn Old Prussian there is one famous form, namely, poklausīmanas ‘heard, answered’. The reason for its renown is that it is regarded by some to be a present passive participle, and, by the same token, directly continue the Proto-Indo-European medio-passive participle in *-mh1no- as reflected e.g. in Vedic -māna- and Greek -μενο-. However, such a supposition is problematic in a few regards. Firstly, Baltic, like Slavic, knows only present passive participle in -m-, which makes the Old Prussian form, at the very least, enigmatic. Secondly, if OPr. -manas truly reflects the ancestral PIE morpheme, it sheds doubts on the validity of the hitherto reconstructed Proto-Balto-Slavic participial suffix *-ma as reflecting PIE *-mh1no-. In the present paper it is argued that Old Prussian poklausīmanas indeed is a present passive participle and that the suffix -mana- does in fact derive from an earlier *-mna- which, in turn, continues PIE *-mh1no-. As for the shape of the Old Prussian suffix, it is proposed that -mana- contains a secondary anaptyctic vowel as suggested by other evidence. Furthermore, some light is shed on the possibility of reconstructing the Proto-Balto-Slavic participial suffix not as *-ma- but rather as *-mna-, which would be more consistent with the shape of the reconstructed PIE suffix from which it derives.