The article dwells on the issues beset with the comparative analysis of word-building potential of Tajik adverbial prefix ба-and its English equivalents.It is noted that adverb is recognized as an independent part of speech in the languages being compared. However, adverb classification as a special category in these languages is uncertain, their lexical boundaries are wide, and their functional types are diverse. Summing up the results of the analysis, the author concludes that adducing word-building potential of the prefix in question forming Tajik adverbs is of many similarities and differences in certain cases. It is worth mentioning that English equivalents of Tajik derivative adverbs formed by this prefix are not identical and the same-formed ones and some of them are used and translated as simple, derivative and composite ones.
