Anxiety is a normal human reaction to stressful and threatening events in their surroundings but if it doesn’t correlate with inducible stimulus in respect to intensity and duration and if it permanently impairs person’s ability to function normally then we are dealing with pathological anxiety, that is to say, a symptom of one of the anxiety disorders classified in 10th revision of The International Classification of Diseases (ICD-10) or in classification by American Psychiatric Association, DSM-IV. We may consider the etiology of anxiety from psychodynamic, biological and neuroscientific aspect. The foundation of the psychodynamic or psychoanalytic aspect was set by Sigmund Freud through his postulates about tripartite mental structure of personality and ways of forming intrapersonal conflicts in the course of person’s psychosexual development which finally lead to anxiety. His groundwork was furthered by numerous 20th century psychoanalytics such as Adler, Jung, Fromm, M. Klein and Fairbairn, the latter two having formed the object relations theory. If we consider the biological aspects of anxiety development we need to be familiar with the physiology of the brain and the role of the neurotransmitter and neuromodulator system. The most of our findings based on pharmacological research point to the hyperactivity of the noradrenergic core locus coeruleus and noradrenergic neuron pathways of the central nervous system as well as reduced activity of serotonin and inhibitory gabaergic neuron systems which are considered starting points for the causes in somatic and psychological symptomatology of anxiety disorders. Due to the advancement of neuroscience we can pinpoint regions, structures and networks of neuron circles of the central nervous system which are responsible not only for storing, integrating and conditioning the feeling of fear and the consequent somatic manifestations associated with threatening stimuli, but also for the overt expressions of fear and the appearance of anxiety as a result of two contextually bound stimuli. These neuroscientific insights are based on the Pavlovian (classical) conditioning. Modern neuroimaging techniques have located Papez circuit, limbic system and the complex of amygdala cores which is the primary structure responsible for the processes of learning and fear conditioning. Finally, certain genes have been located, the variability of which in expression of ‘visceral brain’ neurons modulates remembrance of fear and somatic reactions to anxiety. These genes also represent the potential focal points for future pharmacotherapeutic solutions for the treatment of anxiety and anxiety-connected psychic disorders.