International large-scale assessments have gained much attention since the beginning of the twenty-first century, influencing education legislation in many countries. This includes Spain, where they have been used by successive governments to justify education policy change. Unfortunately, there was a problem with the PISA 2018 reading scores for this country, meaning the OECD refused to initially release the results. Therefore, in this paper we attempt to estimate the likely PISA 2018 reading scores for Spain, and for each region within. The figure finally published by the OECD for Spain - in terms of reading scores - was 476.5 points, which is between the lower and upper bound of the interval we find (475 to 483 test points in 2018). Additionally, we report some robustness checks for the OCED countries participating in PISA 2018, which show that the difference between the actual scores and the ones we found with the imputation methods are quite close.