The potato tuberworm, Phthorimaea operculella (Zeller) (Lep.: Gelechiidae), is one of the most important insect pests of potato crop (Solanum tuberosum L.) in the field and storag environments. At the present chemical methods are used to control this pest. Due to adverse effects of pesticides, researchers in most countries are investigaling medical plants extracts to control this pest. In this research methanol extracts of two medicinal plants, Sophora alopecuroides L. and Eruca sativa Mill. and two Neonicotinoid insecticides, thiacloprid and efuria were investigated for their toxicity against the eggs of potato tuberworm. The bioassay was conducted with 5 different concentrations and 4 replications at 25±2ºC, 65±5% RH and 14:10 (LD) h condition. For this purpose, 20 eggs of potato tuberworm eggs were dipped in various concentrations of plant extracts and insecticides for 5 seconds and then were placed in inside petri dishes. Eggs were counted after the incabation period. The results showed the calculated LC25 value for S. alppecuroides and E.sativa extracts and two insecticides, thiacloprid and efuria were 43654, 60176, 69 and 836 ppm and the calculated LC50 value were 67426, 89819, 134 and 2115 ppm respectively. It can be concluded that the toxicity effects of the extracts of medicinal plants that were stadied in this bioassay on the eggs of potato tuberworm were very lower that two Neonicotinoid insecticides. However, the extracts of the studied plants can also be used in the IPM of the potato tuberworm, because they its showed toxicity on the eggs of this pest.