The invention relates to a method to display page by page a roll-down message in a display zone of a viewer in an aircraft's cockpit, comprising, for each message, the following operations: selection of a full length for the message to be displayed, selection of a visible length for the message to be displayed in the display zone, selection of a repeated length for the message, this repeated length being the length displayed in a current page and copied again into the next page, determination of a total number of pages to be displayed in order for the total length of the message to be displayed with the selected repeated lengths, such total number of pages being determined in the following manner: Np = lower_full ⁢ _part ⁢ ( Lm - Lv + 2 ⁢ Lc - 1 Lc )  with Lc=Lv−Lr,  where Np is the total number of pages, Lm is the total length of the message, Lv is the visible length of the message in the display zone, Lr is the repeated length of the message and Lc is the non-repeated length of the message. The invention also relates to a device for implementing this method.