The paper discusses Witold Mańczak’s hypothesis concerning a Finnic (particularly Balto-Finnic) substrate in the Baltic languages (Mańczak 1990: 29–38, 1993: 151, 2008: 149–152), as well as Jan Henrik Holst’s critical evaluation of the problem (Holst 2015: 151–173). Mańczak lists ten arguments in support of the substrate theory: According to Meillet (1925: 100–101), the disappearance of the neuter gender in Lithuanian and Latvian occurred under the influence of Balto-Finnic languages, since the category of gender is absent from Finno-Ugric. Old Lithuanian displays secondary local cases (i.e. illative, allative, adessive, inessive) formed using postpositions, following the Finno-Ugric pattern (Meillet 1925: 101). Lithuanian constructions expressing evidentiality (e.g. Lith. nešęs velnias akmenį ‘a devil is said to have brought a stone’) – as well as their Latvian counterparts – appeared due to substrate influence, according to Pisani (1959: 217). Lithuanian numerals 11–19 ending in -lika (e.g. Lith. vienúolika ‘eleven’, dvýlika ‘twelve’, etc.) are of substrate origin (ibid.: 217). Lithuanian imperative particle -ki or -k (e.g. OLith. dúoki ‘give’) reproduces a similar particle known from Finnish, according to some scholars (Toporov, Trubačev 1962: 249–250). The alternation of voiced and voiceless consonants, as in blekai/plekai ‘tripe’ (Kiparsky 1968: 76–90 lists 200 such doublets in Latvian and 50 in Lithuanian), may be caused by the influence of a Finno-Ugric substrate, since the Finno-Ugric languages used to lack voiced consonants. There are Common Baltic terms of Finno-Ugric origin, e.g. the name for ‘amber’: OPrus. gentars, Lith. giñtaras, Latv. dzĩtars m. ‘amber’ (Bednarczuk 1976: 47–48). The use of the genitive instead of an adjective in East Baltic (e.g. Lith. lietuvių kalba ‘Lithuanian language’, Latv. latviešu valoda ‘Latvian language’), unknown to other Indo-European languages, arose through Balto-Finnic influence – cf. Finnish suomen kieli ‘Finnish language’, Est. eesti keel ‘Estonian language’ (Bednarczuk 1968). The territory of Latvia abounds in hydronyms of Finnic provenance, while in Lithuania we may identify the name Nemunas (the main river in the area) as well as ca. 30 other river names of potential Finno-Ugric origin (Zinkevičius 1984: 155). The non-distinction of grammatical number in third-person finite verb forms in Lithuanian, Latvian and Old Prussian was, according to some researchers (e.g. Thomason, Kaufman 1988: 243), caused by Balto-Finnic influence. Besides, the present author reviews Holst’s critical paper on the hypothesis about Uralic substrate in Common Baltic. [ABSTRACT FROM AUTHOR]