The Panama Canal region is susceptible to non-native species introductions due to the heavy international shipping traffic through
the area. Ascidian introductions are occurring worldwide but little is known about introductions at the Panama Canal. Surveys were
conducted in 2002, 2008, and 2009 within the Pacific and Atlantic entrances to the canal. We found a high diversity of ascidians on
both sides of the canal, dominated by non-native species; six species occurred at both Pacific and Atlantic Panama sites. This is the
first report of Polyandrocarpa anguinea and P. sagamiensis in Atlantic Panama waters and Ascidia incrassata, Ascidia sydneiensis,
Botrylloides nigrum, Botryllus planus, Didemnum perlucidum, Diplosoma listerianum, Microcosmus exasperatus, Polyandrocarpa
zorritensis, Polyclinum constellatum, Symplegma brakenhielmi, Symplegma rubra, and Trididemnum orbiculatum in Pacific Panama
waters. The canal may serve as a major invasion corridor for ascidians and should be monitored over time.