The dataset contains the monitoring data on abundance and biomass of four gelatinous zooplankton species (<i>Mnemiopsis leidyi, Beroe ovata, Aurelia aurita, Pleurobrachia pileus</i>) from January 2000 to December 2011 in Sevastopol Bay and inshore waters off the Crimean coast (about 2500 records). Gelatinous zooplankton was collected at 5 stations in Sevastopol Bay and 3 stations in inshore waters near Sevastopol.