The study aims at evaluating health-generating function of humor therapy in a hospital ward hosting children suffering from respiratory pathologies. The main scope of this study is to investigate possible positive effects of the presence of a clown on both the clinical evolution of the on-going disease, and on some physiological and pain parameters. Forty-three children with respiratory pathologies participated in the study: 21 of them belonged to the experimental group (EG) and 22 children to the control group (CG). During their hospitalization, the children of the EG interacted with two clowns who were experienced in the field of pediatric intervention. All participants were evaluated with respect to clinical progress and to a series of physiological and pain measures both before and after the clown interaction. When compared with the CG, EG children showed an earlier disappearance of the pathological symptoms. Moreover, the interaction of the clown with the children led to a statistically significant lowering of diastolic blood pressure, respiratory frequency and temperature in the EG as compared with the control group. The other two parameters of systolic pressure and heart frequency yielded results in the same direction, without reaching statistical significance. A similar health-inducing effect of clown presence was observed on pain parameters, both by self evaluation and assessment by nurses. Taken together, our data indicate that the presence of clowns in the ward has a possible health-inducing effect. Thus, humor can be seen as an easy-to-use, inexpensive and natural therapeutic modality to be used within different therapeutic settings.