This article is an investigation of buckling of cold-rolled gusset plates subjected to cyclic axial load for various unsupported length-to-thickness ratios (L/e). A total of twelve specimens were tested and their respective time-to-failure (in terms of the number of cycles) were measured. Using the data obtained, the dependence of time-to-failure on the ratio L/e was investigated. The dependence of time-to-failure on the L/e ratio is important and can be rationalized via an equation through analyses and test results. Such an equation will especially be helpful in design and can be used, along with other requirements, for the selection of an appropriate size for a gusset plate. The paper draws conclusions based on the limited test results and discusses the importance of L/e and cyclic loads in design of gusset plates in bridges.