none Azadirachtin, an azadirachtin-free fraction and enriched, formulated neem seed kernel extracts (MTB/H-2O, AZT-VR-K), which are effective against various lepidopterous pests, proved to be not harmful to adults of Apanteles glomeratus (L.), the most important gregarious larval parasitoid of Pieris brassicae (L.). Concentrations of 10 and 20 ppm/l of azadirachtin, of an azadirachtin-free fraction and of 50 and 100 ppml/l of an enriched product (AZT-VR-K) are, under laboratory conditions, only slightly harmful to the parasitoid, provided they are applied against the 5-th larval instar of P. brassicae. Under these circumstances numerous larvae of A. gloneratus emerge from their hosts, pupate and hatch as normal adults. However, higher concentrations (40 ppm/l) of azadirachtin and of the azadirachtin-free fraction as well as 50 and 100 ppm/l of the enriched product MTB/H-2O reduce the number of parasitoids considerably. The latter are mainly killed by lack of food and die within their hosts. P. brassicae larvae under the influence of metamorphosis-disturbing neem products do not die immediately after uptake of active principles, but reduce food uptake, leading to an increase of intraspecific competition among the gregarious larvae of A. glomeratus. Direct growth-regulating effects of neem products against A. glomeratus are not very likely as malformations of wings were rare and also observed in control insects. Application of neem products against young (1-3) larval instars of P. brassicae, which may be typical under practical conditions, leads to the death of the caterpillars together which the larvae of the parasitoid. The same is true after application of products based on Bacillus thuringiensis. However, within the framework of the integrated pest control conception, when sprayings against larvae of P. brassicae, in case of low infestation, are postponed and/or carried out with low concentrations of neem products, the latter may prove under field conditions to be less harmful even to a gregarious parasitoid like A. glomeratus.