We investigated the age-metallicity relation using a sample of 5691 F-and G-type dwarfs from RAdial Velocity Experiment Data Release 3 (RAVE DR3) by applying several constraints. (i) We selected stars with surface gravities log g(cm s(-2)) >= 3.8 and effective temperatures in the 5310 <= T-eff(K) <= 7300 range and obtained a dwarf sample. (ii) We plotted the dwarfs in metallicity sub-samples in the T-eff -(J - K-s)(0) plane to compare with the corresponding data of Gonzalez Hernandez & Bonifacio (2009) and identified the ones in agreement. (iii) We fitted the reduced dwarf sample obtained from constraints (i) and (ii) to the Padova isochrones and re-identified those which occupy the plane defined by isochrones with ages t <= 13 Gyr. (iv) Finally, we omitted dwarfs with total velocity errors larger than 10.63 km s(-1). We estimated the ages using the Bayesian procedure of Jorgensen & Lindegren (2005). The largest age-metallicity slope was found for early F-type dwarfs. We found steeper slopes when we plotted the data as a function of spectral type rather than Galactic population. We noticed a substantial scatter in metallicity distribution at all ages. The metal-rich old dwarfs turned out to be G-type stars which can be interpreted as they migrated from the inner disc or bulge.