We investigate the correlations between galaxy properties and environment. From the main galaxy sample of the SDSS Data Release 5, we have extracted 11 163 groups at the linking length R_0_=0.2x({bar}n)^-1/3^=1.97Mpc (where {bar}n is the mean number density of galaxies) by the three-dimensional friends-of-friends (FOF) algorithm, where {bar}n is the mean galaxy density, and compare basic properties of member galaxies of main galaxy groups with those of the main galaxy sample and isolated galaxies in each redshift bin.