The article discusses pseudo-linguistic theories about the kinship of the Estonian language published since the 1920s. The author describes these theories, pointing to their characteristic features and causes of origin, and then proceeds to give an overview of the non-scientific theories of the kinship of the Estonian language devised by Henrik Juhankatti, Arthur Gleye, Edgar Valter Saks, Jüri Härmatare and Oskar-Adolf Põldemaa. All the authors, none of whom are linguists, attach great importance to the Estonian language (resp. Baltic-Finnic languages) in the past, about which there are no corresponding data. They also connect the Estonian language (resp. Baltic-Finnic languages) to the old languages of culture (e.g. Etruscan). These theories have deserved much criticism and they have even been regarded as adverse. The author reaches the conclusion that pseudo-linguistic theories are not necessarily detrimental, but should rather be treated as folkloric manifestations deserving to be studied.