Artificial insemination is widely used for livestock breeding. Although sperm cryopreservation is the most efficient method for long-term storage, its use for AI is marginal, because of its dramatic impact on sperm quality. While the removal of seminal plasma is a routine practice before cryopreservation, its beneficial role on sperm function has been less investigated. In this context and despite seminal plasma being regarded as a mere vehicle of sperm, mounting evidence indicates that it could be positive for sperm fertility. In effect, not only is seminal plasma able to interact with female reproductive tract after mounting/insemination, but it has been demonstrated that modulates sperm function. For this reason, the composition of this fluid and its proteome have been exhaustively investigated in order to elucidate whether its components play any role in sperm function, fertility and cryotolerance. On this basis, previous research has demonstrated that seminal plasma may maintain the quality and fertilizing ability of frozen-thawed boar spermatozoa when added before or after cryopreservation. However, a large variety of results have been reported with both beneficial and detrimental effects, including studies in which no influence has been observed. Thus, this review aims look at the composition of seminal plasma and to summarize the available evidences regarding seminal plasma supplementation to sperm before or after freeze-thawing. The take-home message of this article is that clearing up the role of seminal plasma on sperm cryotolerance may increase the efficiency and reproductive performance of frozen-thawed boar spermatozoa.