ABSTRACT. – Spiders are an important group of invertebrates in agroecosystems as they are predators of harmful crop insects. Their use in biological control requires a well understanding of their ecology. Few spiders studies have been done in Algeria, but none was for agroecosystems. In the present study, two plots at the Technical Institute of Great Crops (TIGC) localized at Oued Smar (Algiers) were investigated. The first one is a wheat field and the second one is an oilseed rape field. The activity and the migration of spiders were also studied. In total, 2036 adults were collected (1498 males, 538 females) belonging to 18 families, 52 genera and 81 species. Diplocephalus graecus (Linyphiidae) was the most abundant species with 627 specimens. The spider fauna is more diverse at the rape field than in the wheat crop. This might be due to the intensified agricultural practices in the wheat field. There is also a higher diversity at the edges of wheat crops with fairly stable spider communities. This may be related to the diversity of the flora that offers different microhabitats and several niches for different spider species.