  We discuss the implication of the observation of supernova relic neutrinos on
the study of the star formation rate (SFR) in galaxies. The limit recently
obtained at Super-Kamiokande (SK) is already marginally significant: The SFR we
derived $\psi(t_0)<0.040M_{\odot}$yr$^{-1}$Mpc$^{-3}$(at a 90% CL) is about
twice the SFR estimated from radio observations, and five times the rate from
H$\alpha$ allowing for uncertainties in the model supernova neutrino flux.
