The authors present a surgical technique using a collinear reduction clamp through the modified ilioinguinal approach (MIA) for anteromedially displaced acetabular fractures along with the surgical outcomes. Between October 2010 and June 2015, 15 patients underwent surgical treatment for anteromedially displaced acetabular fractures; 10 both-column fractures and 5 anterior column and posterior hemitransverse fractures. Anteriorly displaced anterior column fragment and medially displaced quadrilateral plate fragment were simultaneously reduced using a collinear clamp and fixed with a 3.5mm-reconstruction plate through MIA. Postoperatively, anatomical reduction was achieved in 12 patients, while imperfect reduction was achieved in 3. At a mean follow-up of 49.0 months (range, 24–93 months), the mean Postel Merle d’Aubigné score were 16.3 and the mean VAS score was 0.9. Final radiographic grades according to Matta system were excellent in 13 patients and good in 2. Surgical technique using a collinear reduction clamp through the MIA can provide satisfactory outcomes in anteromedially displaced acetabular fractures.