Rampazzo et al., 2005, Cat. <J/A+A/433/497> (Paper I) presented a data-set of line-strength indices for 50 early-type galaxies in the nearby Universe. The galaxy sample is biased toward galaxies showing emission lines, located in environments corresponding to a broad range of local galaxy densities, although predominantly in low density environments. The present addendum enlarges the above data-set of line-strength indices by analyzing 18 additional early-type galaxies (three galaxies, NGC 3607, NGC 5077 and NGC 5898 were presented in the previous set). We measured 25 line-strength indices, defined by the Lick IDS "standard" system (Trager et al., 1998, Cat. <J/ApJS/116/1>; Worthey & Ottaviani, 1997, Cat. <J/ApJS/111/377>), for 7 luminosity weighted apertures and 4 gradients of each galaxy. This addendum presents the line-strength data-set and compares it with the available data in the literature.