Retention indices were evaluated for one hundred most commonly reported essential oil compounds in gas chromatography (GC) using a large retention index database. Retention data are presented for three types of stationary phases: dimethyl silicone, dimethyl silicone with 5% phenyl groups, and polyethylene glycol stationary phases. The data evaluations are based on the treatment of multiple measurements with the number of data records ranging between 30 and 470 per compound. Data distribution analysis was limited to temperature programming conditions. Data reported include the most probable value of retention index, average and median values, standard deviation, and confidence intervals. The values of most probable retention indices correspond to frequently used GC conditions of measurements (temperature program, column parameters, gas flow conditions). The results are compared with data from several available retention index collections.