During the autumn 2010 and 2011, at the experimental fields of the Re-search Institute of Horticulture in Skierniewice, the species composition of phy-tophagous insect, occurring on winter onion crop, was determined. Observations were conducted on five cultivars of winter onion: ‘Elody’, ‘Hi-Keeper’, ‘Labra-dor’, ‘Sibir’ and ‘Swift’. Each of the cultivars were seeded in the middle of August, in the area of 240 m2. During the period from the second decade of September (germination of onion) until mid-November (the end of the growing season) were collected and identified onion trips, leek moth and onion fly. Some damage caused by cutworms was also observed. There were no significant differences between cultivars of onions in the number of harmful insect species.