Studies were carried out in maize, cotton, tobacco and vegetable crops in the Andalucia and Extremadura regions of Spain in 1985-87 to determine the noctuid population and that of their associated parasitoids and pathogens. A total of 3450 larvae was collected and only 3 species were recognized (Agrotis segetum was represented by 3376, A. ipsilon by 70 and A. puta by 4 larvae). The incidence of parasitoids and pathogens was directly related to the number of larvae captured. Eleven species of insect parasitoids were recorded, including the braconids Apanteles telengai [Cotesia relengai], Macrocentrus collaris and Zele sp., the ichneumonids Amblyieles sp., Campoletis annulatus and an ectoparasitoid and the tachinids Gonia bimaculata, Linnaemya sp., Peleteria rubescens and Periscepsia carbonaria, were recorded on Agrotis segetum. C annulatus is a new parasitoid record on A. segetum, and Cotesia telengai, P. carbonaria and G. bimaculata are new records for the Spanish fauna. Six entomopathogens (a granulosis virus, a nuclear polyhedrosis virus, Bacillus thuringiensis, Entomophthora megasperma, Nosema sp. and Steinernema sp.) attacked A. segetum, the incidence of the viruses being highest. A. ipsilon was parasitized by the braconids M. collaris and Meteorus rubens and a species of the ichneumonid genus Amblyteles; Meteorus rubens was a new-record. for the Spanish fauna. A species of Steinernema was also found attacking Agrotis ipsilon. A. puta was only parasitized by P. carbonaria. none