During the last two years we have become increasingly aware of a syndrome of left-sided anterior chest pain in young healthy individuals. There is much literature on the differential diagnosis of precordial pain, but we have been unable to find any clear-cut references to the relatively common symptom complex here discussed, which we have termed "precordial catch." The following case history presents its essential features. REPORT OF A CASE A 24-year-old housewife complained of recurrent attacks of severe left anterior chest pain. The pain, described as sharp and knife-like, was felt just below the left breast. It had occurred four times in the preceding two days. The first episode was typical. The patient was relaxed in an easy chair watching television when she suddenly experienced a sharp, severe pain under the left breast. This pain remained localized and caused her to hold her breath. Attempts to breathe were associated with