Abstract This study was carried on the basic of physico-chemical parameters, Scyphozoa and. Ctenophora succession in the Harbour of Çanakkale (40° 09' 07" N, 26° 24' 09" B) between January 2000 and December 2000 sampling intervals. According to the results of chemical analysis; nitrate nitrogen ranged within 0.80-1.630 mglt 1, total inorganic phosphate 0.016-0.044 mglt 1, silica 0.180- 0.300 mglt 1, potassium 190-220 mglt', zinc 0.030-0.1.4 mglt 1, temperature 7.925,1, DO 8.30-9.60 mglt"1, and lead 0.064 mglt' (Table 1). In spite of observing Rhizostoma pulmo rarely, Aurelia aurata could be seen intensively in winter and spring period along the Harbour, Pelagia noctiluca was found rarely in the Harbour during winter and generally during spring. Beroe ovata (Ctenophora) appeared generally during spring and intensively in summer period (Table 2).