Effective length is the length of the equivalent pin ended column, which has the samernelastic buckling load as the actual column. The effective length method has been used forrnmany decades as the basis for the design of columns made of reinforced concrete, structuralrnsteel or steel-concrete components. The underlying assumption with this method is thernsweeping generalization that; because the actual column and the equivalent column have thernsame elastic buckling load, they also posses the same design resistances in the ultimate limitrnstate. This assumption has been the subject of many investigations and it was found out that,rnalthough the method gives reliable results that lie on the safe side in many cases, it couldrnsometimes lie on the unsafe side. The present investigation deals with slender reinforcedrnconcrete columns with linearly varying cross-sections. The effective length method for suchrncolumns poses an additional complication. That is; unlike prismatic columns, the choice ofrncross-section for the equivalent column is not straight forward since the cross-section ofrnactual column is not constant. The results of the present investigation which is limited to pinrnended columns with equal and opposite end moments, have shown that the effective lengthrnmethod gives reliable results if the cross-section of the equivalent column is chosen as perrncertain rules and computations indicated in this document. Extensive tables are compiled forrnthe determination of equivalent section and effective length for any pin-ended tapered columnrnwhich has the same and opposite end moments. Computer programs, which are done usingrnFORTRAN (FTN95) programming language and MICROSOFT EXCEL spread sheets arernused as a supporting tools for analysis processes committed in this investigation. The result ofrnthis research can be taken as an approach, which replaces the cumbersome and lengthy way ofrntraditional iterative analysis for tapered columns.rnKEY PHRASES AND WORDS:rnEffective length, Elastic buckling load, Equivalent section, Failure node, Moment-curvature,rnsecond order analysis, Slender columns, Stabilized length, Tapered column.