The anthelmintic activity of fruit extracts of an Indian Medicinal plant Syzygium cuminii Linn. was evaluated on earthworms of Pheretima posthuma. This is because earthworms have anatomical and physiological resemblance with that of intestinal roundworm parasites of human beings. Here anthelmintic activity of the herb was determined by time taken for paralysis and death of earthworms after suitable treatment and comparison with standard drug piperazine citrate. The ethanol extract of Syzygium cuminii fruit at concentration of 50 mg/ml showed most pronounced activity. The results suggest that fruits of Syzygium cuminii possess anthelmintic activity. There is scope for future study on this plant.