<p>The current consensus regarding intracellular RNA trafficking in eukaryotic cells is that RNAs transcribed in the nucleus either remain in the nucleus or cross the nuclear envelope, entering the cytoplasm for function. However, new evidence suggests that many functional RNAs move in the opposite direction, from the cytoplasm to the nucleus. The process behind RNA nuclear import is not well understood. Viroids are plant-infecting single-stranded circular noncoding RNAs. We demonstrated that cellular IMPORTIN ALPHA-4 (IMPa-4) is likely involved in viroid RNA nuclear import using Nicotiana benthamiana, tomato (Solanum lycopersicum), and nuclear-replicating viroids as a model, empirically supporting the involvement of Importin-based cellular pathway in RNA nuclear import.</p><p><br></p><p><br></p>