We conducted a first experimental study on the psychological effects of thermal baths – a topic of great interest for environmental psychology, health psychology and the study of psychological evaluation techniques. The so-called Terme dei Papi (“Pope’s Baths”), situated in Viterbo, about 90 kilometres north of Rome, were chosen as the setting. The study saw the participation of 44 young adults, both genders equally represented, aged 19-29 y. (average age: women y. 23.7; men y. 23.5). Three coach trips were made on sunny springtime days with fifteen participants each time. Each participant first compiled the “Self-Appraisal Scales”, which are 7-point bipolar scales for evaluating emotional and motivational states. They then made a so-called “Stress Drawing” – a drawn recalling of personal stress experiences, with ample drawing and colouring materials available. They then went into the thermal bath for about an hour. Immediately after they again compiled the “Self-Appraisal Scales” and made a “Stress Drawing”, focusing on the same situation recalled previously and as it appeared to the subject now. The computation of the differences between their pre- and post-treatment performances showed a significant reduction in emotions of anxiety, anger, sadness, suffering, disgust and embarrassment; a decrease also in feelings of stress, dissatisfaction and insecurity, and a reduction also for some needs such as the need for explanations and for body movement, which characterise typical levels of stress. Their nutritional needs appeared increased. The above variations, by means of the Student t test, showed levels of significance from p