An interesting feature of the olfactory system is its relationship with the respiratory system. The research studies have shown that olfactory imagery increases respiratory tidal volume, resulting in an improvement in respiratory function. This paper systematically reviews the effectiveness of mental imagery on respiratory function. Twelve electronic databases were searched from their inception through the end of January 2015. Our literature search was limited to English and Persian databases, using the predetermined keywords to find the existing evidence on the effectiveness of mental imagery on respiratory function. The selection of articles, data extraction and validations were performed by two independent reviewers. The search yielded 69 articles, 7 of which met the inclusion criteria. No additional article was identified from the bibliographies of retrieved papers. Despite very little research on olfactory imagery, the evidence indicates that this imagery approach can improve respiratory function by stimulating sniffing and subsequent increase in respiratory volume and depth. However, further research is required to provide evidence of the effectiveness of mental imagery in cases such as respiratory muscle weakness or decreased respiratory function.