He exposed a number of regularities in the historical phonetics of Hungarian, and substantiated the existence of grammatical and lexical Ugro-Samoyedic parallels.
He proposed a number of novel Uralic, Indo-European and Nostratic etymologies, and collected a large body of material on the borrowed lexicon of the languages of Siberia (including Russian).
[2] Helimski proposed a number of modifications to the traditional theory of the "genealogical tree" with respect to the Uralic data, which affected comparative studies in general.
He published several editions of "Таймырский этнолингвистический сборник" ("Taimyr Ethno-Linguistic Compendium", RSUH) and other works on Uralistics.
Helimski initiated the development of a digital database of Uralic, which later became part of Sergei Starostin's StarLing Project.