EN
The subject of this paper is the probative force of the clause on mental health of the testator, usually posted by the writers writing down the content of the oral disposition of the testator’s last will. The answer to the question whether such a clause really proves the testator’s mental health is important because health was one of the legal requirements for the validity of a will. The considerations will concern wills drawn up in accordance with the municipal law of pre-partition Poland. After presenting the institution of the will in the light of Magdeburg law, the author discussed reflections of Pedro Ruiz de Moros on the importance of certifying the testator’s mental health by the city writer. The conclusions were placed at the end of the paper.