Ecological and geomorphological factors that control the distribution of Lepidopterous insects were thoroughly examined in three different areas of Egypt. These areas are Senoris, Fayoum Governorate; Al-Arish, North Sinai Governorate; and Kharga Oasis, New Valley Governorate. One hundred and ninety two species belonging to 143 genera represent in 23 families were recorded. The study of similarity between the three areas was carried out using Sørensen equation. The results indicated that there are significant differences between these areas. Similarity in species copmposition nonetheless, is the highest among Fayoum and Al-Arish areas (70%), followed by Fayoum and Kharga Oasis (64%). The least similar areas were Al-Arish and Kharga Oasis (57%). Al-Arish has the highest number of characteristic species (41 species) forming 42.27% of the total number of the recorded characteristic species; while Fayoum has the least number of characteristic species (20 species) comprising 20.62% of the total. New Valley has 36 species representing 37.11%. Eleven new-recorded species were collected during this study, one belongs to family Elachistidae “Leucoptera scitella Zeller", five belongs to family Noctuidae “Acontia hortensis Smith, Clytei syriaca (Bugnion), Agrotis sordzeana Brondt; Nola harouni Wiltshire, Eulocastra diaphora Staudinger", one belongs to family Pieridae “Colias hyale L.", and four belonging to family Pyralidae “Staudngeria yerburii Bulter, Hypotia colchicalis H.-Sch., Parastenia daradis (Chretien), and Synaphe marbidalis Guenée".