The regulation of stress by an attachment figure is a key feature of attachment relationships. Previous research suggests that in some cases animal companionship may be regarded as an attachment relationship. This may be particularly important for persons with an insecure or disorganized attachment pattern who may find it more difficult than securely attached individuals to accept social support from humans. In our study, we investigated whether 31 boys (aged 7-12 years) with insecure/disorganized attachment would profit more from the presence of a dog (n = 11) than of a friendly human (n = 11) or a toy dog (n = 9) as support during a socially stressful situation (Trier Social Stress Test for Children, TSST-C). Stress levels were assessed via salivary cortisol recorded five times before, during, and after the TSST-C. The behavior of the children was coded from video recordings. Self-reported stress levels did not significantly differ between the groups before and after the TSST-C. Salivary cortisol, however, was significantly lower in the real dog condition than in the other two conditions (Kruskal-Wallis H test on area under the curve increase (AUCi): chi(2) = 15.17, df = 2, p = 0.001). Also, the more the children stroked the dog, the less pronounced was their stress reaction (r(s) = -0.818, p = 0.002). Our data suggest an important role of physical contact in the stress reducing effect. We conclude that the children investigated profited more from interacting with a friendly dog than with either a human or a toy dog in a stressful situation. We discuss the relevance of our findings for animal-assisted interventions.