The fear of being laughed at brings to the fore the problematic side of an otherwise very positive aspect of human experience. In the streamline of investigations analyzing the presence and characteristics of gelotophobia, a study focusing on psychiatric patients was carried out. The diagnoses were established according to the criteria of the DSM IV TR (American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders (DSM), APA, 2000). Based both on clinical and empirical observations, the main hypothesis advanced was that using the Geloph15 scale, Ss with a psychiatric diagnosis would have higher mean scores than Normal Controls. An additional hypothesis was that intragroup differences were also expected among the various diagnostic categories. The main hypothesis was amply supported, and explanatory suggestions of the finding were proposed. Intragroup differences proved also to be significant. Patients with personality disorders and patients with schizophrenic disorders scored higher than Normal Controls and the other diagnostic groups. And also the number of years spent in psychiatric care resulted significantly associated with higher gelotophobia mean scores. From the present study, a circular, interactive relationship was confirmed between laughter and mental health, which can alternatively be highly positive or deeply negative.