Fundamental period is an important dynamic property of the chimney necessary for use in SEAOC code (Structural Engineers’ Association of California), Rumman’s and S 18931975 code procedures for the design of chimneys subjected to earthquake effects. Various codes in the worid recommend empirical equations for reckoning the same. 1,2,3 In this note a rational method is advanced based on Rayieigh’s minimum principle for computing the period in a realistic manner. Finally a prediction equation is proposed for rapaidly estimating the period in the design office.