The request for proof of use within an opposition procedure in Spain was one of the novelties introduced in 2018 by the reform of the (link: https://www.boe.es/eli/es/l/2001/12/07/17/con text: Trademark Law 17/2001, of December 7, 2001), for the transposition of (link: https://eur-lex.europa.eu/legal-content/ES/TXT/?uri=CELEX%3A32015L2436 text: Directive 2015/2436 of the European Parliament and Council of December 16, 2015). However, its entry into force had to wait until May 1st, 2019, after its regulatory development in (link: https://www.boe.es/eli/es/rd/2019/04/26/306 text: RD 306/2019 of April 26th, amending the Regulation for the implementation of the Trademark Law). Furthermore, the practical application of the procedures contained in the new regulations has had to wait for the implementation of the electronic tools and resources by the Spanish Patent and Trademark Office, so that both owners and representatives can comply with the compulsory procedures. We recall that, in the framework of an opposition procedure in Spain, the applicant of a trademark or trade name may request his opponent to submit proof of use of his earlier trademarks. Opposing marks that are the subject of proof of use are only those that, on the date of filing or priority of the contested application, have been registered for more than five years, and which are firm registrations. The applicant may choose to (a) file the arguments in reply to the suspension and the request for proof of use within the time limit set, or (b) file only the request for proof of use and submit the arguments to the opposition together with those made in reply to the proof of use submitted by the opponent. If the second option is chosen, the main advantage is that we obtain more time to prepare the observations against the opposition received. Another advantage is that we will have the possibility to assess the use of the opponent's mark and explore negotiation tracks. Furthermore, this second option makes sense when we believe that the opponent will not submit evidence of use of his mark, or when this evidence will be insufficient, and thus the Office would reject the opposition. A novelty introduced by the SPTO in the proof of use procedure, and which we consider very useful, is the possibility of requesting accelerated processing of the file at the time the applicant files the request, and when the opponent submits the proof of use. On the other hand, the period of one month established by the Regulations under the Trademark Law for the opponent to submit the corresponding proof of use is insufficient. The gathering and selection of the evidence is a tedious task, requiring very close cooperation between the owner of the trademark and his representative, which is not always possible in such a short space of time. That is why on many occasions we will find it difficult to deal with the request of proof of use. Another issue of interest is the assessment of evidence of use concerning opposing marks that are European Union marks. Well, the SPTO must assess their genuine use in accordance with the provisions of the European Union's trademark Regulations. In other words, if in accordance with European Union Law the use of the opposing mark is genuine use, for the opposition proceedings in Spain the use of this mark must be considered proven. The above, even though the trademark is not used in Spain but in other countries of the European Union. To sum up, we must consider that not many procedures of Proof of Use have been initiated before the Spanish Office. Last March, the Office itself estimated that less than 200 requests for use had been filed since the entry into force of the Regulation, and only 5 submissions were forwarded to the applicant. This suggests that we are dealing with an under-exploited procedure, and that we must wait to know the criteria applied by the Spanish Office. For the time being, no Guidelines are available in this regard, which means that it will be up to the owners and representatives to follow very closely the practical implementation in this area until this procedure ceases to be the novice of trademarks in Spain.