In this paper we investigate the hot end of the horizontal branch (HE)
, presenting evolutionary constraints concerning the C-M diagram locat
ion and the gravity of hot HE stars. According to the adopted evolutio
nary scenario, we predict an upper limit for HE temperatures of about
log T-e = 4.45, remarkably cooler than previous estimates. We find tha
t such a theoretical prescription appears in good agreement with avail
able observational data concerning both stellar temperatures and gravi
ties. Finally, the problem of gaps in the HE distribution is discussed
, suggesting that, at least in the case of the cluster NGC 6752, evolu
tionary gaps, a bimodal distribution of CNO, and stellar rotation shou
ld all play a negligible role.