For a country like Tunisia, drought is probably the most feared phenomenon of the expected climatic change during the XXI century. The present work, based on simulation results of the most recent general circulation coupled model HadCM3 of the Hadley centre, aims to encode and to specify the severity of the phenomenon. The methodology is based on: (i) the analysis of the variations of the yearly and seasonal average precipitations, (ii) the calculation of ratios concerning the deciles medians in order to analyse years and extreme seasons, and finally (iii) deviation from averages of the considered climatic period. Horizons years are 2020 and 2050 and variations are referenced to the 1961-1990 climatic period. Main results show: (i) slight decreases in precipitation means, around 5 to 10% from north to south on the horizon 2020 and more pronounced reductions, 10 to 30% on the horizon 2050; (ii) decreases of the averages of the very humid and very dry years are expected as well as decreases for springs and very humid and very dry falls; (iii) a global increase of dry years as well as of their successive occurrence two and three in the central and southern part of the country; and (iv) higher disparities between seasons and geographical regions of the country especially on the horizon 2050. These results indicate an accentuation of droughts in Tunisia for the future horizons in relation to the 1961-1990 climatic period and come to specify and to confirm previous works in this domain.