This work describes and analyzes possible modifications in the mathematical Argumentation in one hundred andthirty seven (N=137) textbooks for secondary school students published between 1940 and 2007. The notion ofArgumentation proposed by Leitão (2001; 2007) is adopted and used to describe the characteristics of thetextbooks. The analysis of the textbooks facilitates the observation of different ways to base on and conceiveMathematics according to the year of edition. This change is described according to Traditions of theMathematical in the sense proposed by Klimovsky and Boido (2005).The mostly used and representative textbooks in the secondary school in the Argentinean Educational System areselected by an intentional sample. Taking into account categories and subcategories of analysis, a qualitativedescription is made of the characteristics of textbooks and of the Argumentation. Assuming a broad notion ofargumentation, it may be stated that there would be modifications in the form to initiate it, in the types ofreasoning and in the situations proposed in relation to the way Mathematics are conceived. Besides, there arechanges in the quantity and quality of images used in recent editions. Some considerations about how externalrepresentations would affect Mathematical Argumentation are made. On the other hand, if the explicitconfrontation of points of view is assumed as a necessary condition to define argumentation, it is concluded thatneither of the textbooks would be argumentative. This leads to reflect about the proportion between informativeand strictly argumentative aspects that are involved in a textbook.