Torrential floods are the most frequent phenomenon in the arsenal of 'natural risks', in Serbia (droughts, avalanches, landslides, rockslides, hail, forest fires, storm wind and earthquakes). Regime of occurrence of floods was studied on the basis of investigations carried out on 128 control profiles, on all important river systems in Serbia, south from Sava and Danube. Frequency of event of maximal discharge Qmax, over determined threshold, defined as average maximal discharge Qmaxsr, was analyzed. The primary maximum of frequencies was noticed in the period May-June, and the secondary maximum of frequencies in the period February-March. The absolute maximal discharges Qmaxa registered on certain profiles follow the periods with the most expressed frequencies, but there are also significant exceptions. A few equations have been derived, which point out close relations between average maximal discharge Qmaxsr, magnitude of the catchment area A, average annual discharge Qsr and the absolute maximal discharge Qmaxa [Qmaxsr=f(A); Qmaxsr=f(Qsr); Qmaxsr=f(A, Qsr); Qmaxa=f(Qmaxsr)]. Historical cases of maximal discharges, reconstructed on the basis of 'hydraulics flood traces' are presented.