Objective: Test if therapy dogs can reduce anxiety in emergency department (ED) patients. Methods: In this controlled clinical trial (NCT03471429), medically stable, adult patients were approached if the physician believed that the patient had “moderate or greater anxiety.” Patients were allocated on a 1:1 ratio to either 15 min exposure to a certified therapy dog and handler (dog), or usual care (control). Patient reported anxiety, pain and depression were assessed using a 0-10 scale (10=worst). Primary outcome was change in anxiety from baseline (T0) to 30 min and 90 min after exposure to dog or control (T1 and T2 respectively); secondary outcomes were pain, depression and frequency of pain medication. Results: Among 98 patients willing to participate in research, 7 had aversions to dogs, leaving 91 (93%) were willing to see a dog; 40 patients were allocated to each group (dog or control). No data were normally distributed. Median baseline anxiety, pain and depression were similar between groups. With dog exposure, anxiety decreased significantly from T0 to T1: 6 (IQR 4-9.75) to T1: 2 (0-6) compared with 6 (4-8) to 6 (2.5-8) in controls (P<0.001, for T1, Mann-Whitney U). Dog exposure was associated with significantly lower anxiety at T2 and a significant overall treatment effect on two-way repeated measures ANOVA for anxiety, pain and depression. After exposure, 1/40 in the dog group needed pain medication, versus 7/40 in controls (P=0.056, Fisher’s). Conclusions: Exposure to therapy dogs plus handlers significantly reduced anxiety in ED patients.