The northeastern region off Taiwan exhibits a high marine diversity favoured by the influence of northern and subtropical water masses driven by the East China Sea Water and the Kuroshio current (KC), respectively. A total of 87 species of copepods representing 36 genera were identified in present study. Calanoida was the most dominant order, while Temora turbinata (Dana, 1849), Paracalanus parvus (Claus, 1863) and Ditrichocorycaeus affinis (McMurrich, 1916) appeared as most dominant species. However, we noticed the unusual presence of the copepod Calanoides philippinensis Kitou & Tanaka, 1969 in concurrence with the dominant influence of KC, which suggests a larger intrusion of South China Sea (SCS) waters into the northeast Taiwan region. C. philippinensis is an exclusive species of the warm subtropical Pacific waters. Its presence in the northern Taiwan region may reflect a larger intrusion of warm SCS waters. We therefore suggest its potential use as a bioindicator of southern, tropical waters in the northern Taiwan area. [ABSTRACT FROM AUTHOR]