A high frequency of suicide ideation (SI) has been reported following traumatic brain injury (TBI) (Simpson & Tate, 2002; Teasdale & Engberg, 2001). This study examined the frequency of SI following TBI, and its relationship to alexithymia, and depression, plus two components of depression—hopelessness and worthlessness. One hundred and five TBI patients and 74 demographically matched controls completed the Toronto Alexithymia Scale-20 (TAS-20) and the Beck Depression Inventory (BDI-II). Ratings of SI, hopelessness, and worthlessness were extracted from the BDI-II. Results confirm a high frequency of SI (33%) and alexithymia (61%) after TBI compared with healthy controls (1.4% and 6.5%, respectively). A high frequency of alexithymia was also found in a sub-group of moderate-severely depressed TBI patients (70.68%) compared with two non-TBI depressed samples (53.92% and 44.8%). A significant association was found between SI and alexithymia in the TBI group, with the SI group reporting significantly higher TAS-20 total scores. However, logistic regression analysis found that worthlessness was the strongest predictor of SI after TBI. The results of this study suggest that increased attention should be directed toward emotional change after TBI, as alexithymia may mediate the development of worthlessness and, in turn, increase the risk of SI. (JINS, 2010, 16, 1108–1114.)