In this paper we compute the values of Gini Coefficient (Gini, 1912; Gini and Galvani, 1929; Kendall and Stuart, 1969), based on actual data of the annual income declarations for all the Greek taxpayers as from 1962 to 2002. We calculate by exponential smoothing the trend of Gini Coefficient and we show that it has an upward direction from 1989 to 2002. Specifically, we show that the gap between rich and poor people had a constant width between the years 1980 to 1989, whereas the same gap has been widened between the years 1990 to 2002. Treating the data as a Time Series, we compute the Residual Standard Error (RSE) based on the method of Quennouille (1949), the so called “Jackknife method of robust interval estimation”. For an extensive bibliography and detailed presentation of the Jackknife resampling method of nonparametric estimation, the interested reader can consult Efron (1979a, 1979b, 1981, 1987), Frangos (1980a, 1980b, 1983, 1984, 1987, 1991, 1994) and Miller (1974). Moreover, we forecast the value of Gini coefficient for 2001 and 2002.