In the face of an observed increase in asthma mortality since the end of the 70's an analysis of the time series of the deaths for the period 1979-89 was conducted; which shows a peaking of mortality between 1985 and 1987. A different seasonal component of asthma mortality has been identified for the age group 5-34 and over 34 group. For the later, mortality was found to peak during winter and dropping to the lowest point in summer, well synchronised with the mortality due to respiratory infection. For the former, mortality usually peaks during summer and troughs during the winter, independently of the mortality due to respiratory infection. A bimodal repartition of deaths was observed in the age group 5-34 with a main peak in summer (July) and a secondary peak in autumn (October). Modeling of the deaths series by season shows a dramatic rise in mortality during the years 1985, 1986 and 1987 affecting both age groups. During these 3 years, the global over-mortality is 21%. The increase has affected all the seasons allowing for seasonal variations of each age group. Factors responsible for the death seasonality in each age group are discussed. The temporary action of a non-specific factor was proposed to explain the cross-sectional character of the mortality crisis in the population; namely the influenza epidemics during the 1985 and 1986 winters.