The effectiveness of physical therapy for treatment of anterior disc displacement without reduction of temporomandibular disorders has not been well defined. This study compared the treatment method with conservative splint therapy. Fifty two subjects were assigned at random to either of two treatment groups: one is a splint treatment group, and the other is a joint mobilization self exercise group. Each treatment was evaluated using four outcome variables: (i) maximum mouth opening range without and (ii) with pain, (iii) present pain intensity, and (iv) limitation of daily activities. All outcome variables were significantly improved after eight-week of treatment in the exercise group. Meanwhile, the splint treatment improved three variables, other than "mouth opening with pain"; however, the degree of improvement was less than that seen in the exercise group. This result demonstrates that the joint mobilization self exercise improves jaw function and relieves pain as compared to the splint treatment.