In this study the progressive collapse behavior of irregular buildings was evaluated by nonlinear static analyses. A tilted building with inclination of 10 degrees, and a twisted building with twist angle of 45 degrees, and prototype regular structures were designed as analysis models and progressive collapse analyses were carried out by removing a first-story column. The analysis results showed that tilted or twisted buildings generally had resistance to progressive collapse caused by the sudden loss of a vertical element. It was also observed that when a column located around a corner in the tilted structure was removed, plastic hinges formed in the upper and mid-height of the building. Similar observations were made in the model structure with twisting angle.