My study presents the entail of the Mailáth family in Perbeník. The estate of Perbeník, which was converted into an entail of the Mailáth family in 1867, was located in the former county of Zemplén, and this former estate now belongs to the Slovak Republic. The Mailáth family moved to Zemplén County in the 18th century, via the marriage of Joseph Mailáth III. He married one of the daughters of the Sennyey family, the greatest landowner of the time. József Mailáth III., through his marriage with Antonia Sennyey, received the Sennyey estates in Zemplén County, and subsequently, established one of the largest manorial centres in Zemplén County. In my study, in addition to the Perbeník estate, I also review the inventories of the Őrhegy and Monyha farms, whereby we can get a relatively detailed picture of the Mailáth family’s estates in Zemplén County, the family trust established in 1867, and the family contradictions surrounding the entail.