Displaced unstable pelvic fractures are commonly associated with disruption of the osteoarticular junction of the sacroiliac joint. Posterior sacroiliac dislocation are commonly reported but there are only few reports the anterior type of sacroiliac dislocation where the iliac bone fractures and displaces anterior to sacrum, often in combination with fractures of pubic rami and symphyseal injuries. We present a case of an anterior type of sacroiliac fracture dislocation which was associated with a lumbar plexus injury involving both motor and sensory components. Preoperative neurological assessment was done by MRI scan. The tented nerve roots were explored and decompressed surgically, and sacroiliac fixation was done after reduction in the fracture and joint.