Due to the high incidence of allergic diseases in Mexico, caused by exposure to pollens, there have been several studies of plants and atmospheric pollens in various regions in the last decades. In the city of Toluca there have been two previous pollen samplings using gravimetric methodology, for which it is necessary to obtain new samplings with a standardized volumetric technique, in order to have updated and confident results of a region with considerable environmental changes in the last years.To determine the different types of pollens, seasonal variations and behavior in the four seasons of the year.A descriptive study, related to the identification of pollens by the suction and trapping of particles with the volumetric sampler type Hirst (Burkard) performed in the city of Toluca, Mexico, from October 1, 2004 to September 30, 2005.Twenty-nine different airborne pollen types were identified, which amounted a total of 13,542 pollen grains. During winter we found the largest number of pollens. The months with the highest and lowest amount of pollens were January and August, respectively. Pollens from trees predominated, mainly from the Cupressaceae (44%) and Pinaceae (13.8%) families, which were present in the atmosphere throughout the year.We identified a larger amount of pollens from trees in winter, mainly from the Cupressaceae family, and it is closely related to the number of trees planted of this species in the city.