Some slope instability problems exist in Ankara clay along E90 highway. The purpose of this paper is to determine the mineralogical and geotechnical properties of soils, and to investigate the causes and mechanisms of three rotational landslides along a section of the highway. In order to accomplish these tasks, field studies, laboratory testing, back analyses, and limit equilibrium and finite difference analyses were performed. The landslides are formed within a soil consisting of clay and silt with a little sand and gravel. Slope stability analyses indicate that long-term stability of already failed slopes is critical. The failures are progressive, showing strain softening behavior with full saturation. Broken irrigation pipes existing near the landslides are found to be the main cause of sliding. Maintenance of the pipes, surface drainage, removal and replacement of the failed (slided) material are considered to be economical and practical solutions for the remediation of the slides.