Background: Somatic illness and its consequences evoke strong emotions of various kinds. They may affect the course of illness and the treatment results through their physiological components. The purpose of the study was to explore emotional reactions to different kinds of illnesses and changes of these emotions over time. Methods: Subjects were 259 medical patients suffering from: primary hypertension, myocardial infarction and cancer of the lungs or pharynx. The study was longitudinal and consisted of three phases. The first was performed immediately after the patient was diagnosed, the second was done 5 weeks later and the third about half a year after the onset of illness. The patients’ emotional state was evaluated with the Gottschalk-Gleser Content Analysis Scales: the Anxiety and the Hope Scales. Results: Significant effects of the kind of illness and of its interaction with the phase of the study were found. In the hypertension group, both anxiety and hope were slightly elevated immediately after diagnosis, then slightly lowered. The myocardial infarction group exhibited a low level of these emotions in the first phase, an increase in the second and then a little decrease. Cancer patients manifested high anxiety and relatively low hope in the initial phase, then a decrease in anxiety and an increase in hope. Conclusions: Both anxiety and hope accompany the illness in its consecutive phases, reflecting properties of illness as a source of psychological stress and the coping process.