The Kouchibouguac Bay barrier island – sand spit system is the simplest of the four large systems in the southern part of the Gulf of St. Lawrence, and occupies a relatively low wave energy environment. Present field evidence and information from a series of maps published since 1807 and a series of air photographs taken since 1930 indicate that the barriers have undergone considerable changes over the last 160 years. The changes involve shoreward retreat and repeated breaching and infilling of a series of temporary inlets. The three main inlets in the system have remained relatively constant in overall position during this period, but there have been marked local variations in the associated channels and shoals. In general terms the Kouchibouguac barriers may be considered as representative of other systems in the southern part of the Gulf of St. Lawrence and present strong similarities to the well documented barriers of the eastern coast of the United States.