A column is said to be slender if its cross-sectional dimensions are small compared with its length, and its strength is reduced by second-order deformations. Several methods are available for slender column design including codes and researchers. A number (135) of slender column tests is used in this work; from the literature are reanalysis by different methods. Using these tests’ results new proposal formulae are made for slender column design. When compared to existing methods the proposed one gives better correlation with test results. The proposed methods were derived using regression analyses for the based on different parameters. Theoretical analyses of columns are sampled to study the major variables affecting the column for each method of analysis. The paper is mainly concerned with making suggest and comparison between several methods analyzing slender columns.