A 24-year-old man acquired a color vision defect shortly after an accident in which he struck the back of his head. Results of the Farnsworth-Munsell 100-hue test showed that the patient had poor color discrimination in both eyes. His color matches on the Nagel anomaloscope suggested a red/green disturbance. Results from increment threshold testing demonstrated on absence of the blue mechanism. Results of field sensitivity measurements confirmed that foveal vision was mediated by the red or green mechanism. This case showed both similarities and differences to previously reported cases of acquired color vision defects secondary to cortical trauma.