  Quasars are among the most luminous objects in the universe, and they can be
studied in detail up to the highest known redshift. Assuming that the gas
associated with quasars is closely related to the interstellar medium of the
host galaxy, quasars can be used as tracer of the star formation history in the
early universe. We have observed a small sample of quasars at redshifts 3<z<5
and present results using NV/CIV and NV/HeII as well as MgII/FeII to estimate
the date of the first major star formation epoch. These line ratios indicate
solar and supersolar metallicities of the gas close to the quasars. Assuming
times of tau_{evol} = 1 Gyr the first star formation epoch can be dated to z_f
>= 10, corresponding to an age of the universe of less than 5*10^8 yrs (H_o =
65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7).
