Argentina has a long tradition as a beef producer country. Cattle in particular, have played a major role in the traditional environment as a source of food, employment and savings. Many of the typical symbols of this country are found within an environment of ranches, cowboys, horses and cattle, called in Spanish: Estancias Gauchos, Caballos and Ganado. The cattle sector not only represents a source of food, employment and savings to many people in Argentina, but is also a social symbol which the Argentines are proud of and identify with. Cattle can be sold at the ranch or at any city market. The selling and buying operations are performed through open auctions. If the animal is sold for fattening, the price is set per head. When it is going to slaughter the animal or group of animals are weighed and sold per kilogram. From 10 to 25 percent of the production is exported, the rest is consumed mostly as fresh meat. Agricultural production represents approximately 13 percent of Argentina's gross national product and nearly 50 percent of the value of agricultural production comes from meat production. Complex interactions between supply and demand in a market cause prices to change constantly during the year. Seasonal patterns are also evident in the quantities supplied or demanded of a commodity. The measurement of these variations in quantities or prices have some complications, especially in the cattle subsector. The objectives of the paper are the following: 1) to do research on monthly prices of finished cattle to find out if a seasonal pattern exists for the following five categories of animals: calves, small steers, big steers, cows and heifers; 2) to do research on monthly quantities of slaughtered finished cattle to find out if a seasonal pattern exists for the same five categories; 3) to describe the patterns and present them in an easy and applicable way for decision making; 4) to provide an explanation for the nature of the seasonal patterns; 5) to estimate the variability of prices for each month in a risk analysis framework; and 6) to provide an idea of how the market works as a whole by combing all the seasonal patterns obtained for each category.