Various statistical characteristics of long crested artificial irregular water waves generated in long experimental tanks have been particularly investigated in this study. As that results, the statistical properties on wave heights, wave amplitudes (maxima and minima), wave periods and wave steepness of artificial irregular water waves were widely obtained. The relations between the statistical characteristics by the direct statistical analysis of measured timehistories those estimated properties by the spectral analysis were also clearly shown. Moreover various new knowledges were obtained for following important items, those are probability distribution of wave periods, joint probability of wave heights and wave periods, statistical characteristics of wave steepness and the vertical asymmetry on hidh irregular waves. Finally authors point out, it is considered that the major part of obtained results of this investigation consist not only in the artificial irregular waves but also in the real ocean waves.
