The first report of the present investigation treats several methods of predicting the dynamic behaviour of an articulated column in regular waves. A straightforward solution is to integrate the equations of motion describing the behaviour of a column in waves to obtain timehistories of the motion. However, about thirty to forty periods of oscillations are required for the pitching motion of a column in regular waves to fall into a steady oscillatory state, in other words, for the transient oscillatory motion of a column to disappear. Besides, the phase lag of a column predicted by the direct integration of the equations of motion definitely differs from the experimental results. To the contrary, analytical methods proposed by the authors enables us to calculate the characteristics of frequency response of an articulated column directly and in a short time. Predicted frequency response determined by the analytical method excellently agrees with the experimental results. In addition, it is found that the effect of wave amplitude on the frequency response of an articulated column is negligibly small, as far as the results of present investigation are concerned.