The Pain Discomfort Scale developed and validated by Jensen and Karoly (USA, 1991) is an instrument of 10 ítems which allows the measurement of the affective dimension of pain without the psichometric and practical limitations of the few existing methods devoted to these purposes. In order to introduce and apply it in our country, the scale was translated finto Spanish and adapted according to the criterion of a group of psychologists experts in this topic, later it went through a validation study. The infernal consistency of the 10 ítems scale was low so it was submitted to an analysis to determine the ítems that contributed more and elimínate those that didn't establish differences in relation to patient's behavior in presente of pain. A final 6 ítems version called "Escala de malestar por Dolor" (E.M.D.) was achieved and its validation performed. The infernal consistency of this scale was good indeed and the correlation and factorial analyses supported this opinion, proving its validity and reliability.