Possibilities of biological control were investigated by the use of some antagonists for controlling Erwinia chrysanthemi, the causal agent of soft rot on tomato. Seventy-one candidate antagonists were isolated from tomato rhizosphere in Adana and Mersin sites in Turkey and the remaining seven isolates were obtained from Plant Protection Department in Israel. In petri dishes studies, 14 isolates inhibited E chrysanthemi's growth. Laboratory assays for suppression of soft rot development on potato slices were carried out using all candidate antagonists and 16 isolates prevented development of symptoms of soft rot caused by E chrysanthemi. Thirteen out of 16 antagonist isolates, which prevented the development of the pathogen on potato slices, were chosen for further tests. Their abilities to prevent the disease development were investigated on young tomato seedlings in climate room conditions. Eight out of 13 selected isolates reduced the disease development between 89% and 33%. Greenhouse experiments were carried out using five selected antagonists on tomato plants. One of the antagonists provided a good level (74% protection) on tomato plants against E. chrysanthemi in the greenhouse experiments. The present study is the first report on the efficiency of potential biocontrol agents against tomato bacterial pathogens in Turkey. (C) 2003 Elsevier Science Ltd. All rights reserved.