Abstract The study was carried out in olive orchards of Edremit, Havran and Burhaniye districts of Balıkesir province, located in the west of Turkey, between 2019 and 2021 to determine the infection rate, parasitization rate and parasitoids of Olive leaf gall midge, Dacineura oleae Angelini (Diptera: Cecidomyiidae). During the study, the infection status of D. oleae, decreasing from the highest rate, was determined as 55.3% in Edremit, 52.0% in Burhaniye, and 50.7% in Havran. The lowest rate of parasitization was determined in Edremit district with 44.7%, and the highest in Havran district with 49.3%. In Burhaniye, this figure was 48.0%. 10 species belonging to 4 families from the order Hymenoptera parasitizing D. oleae were determined. Of these species; Zeytinus balikesirensis Doğanlar and Sakin, Z. edremitensis Doğanlar and Sakin, and Z. marmarae Doğanlar and Sakin (Eulophidae) were firstly described in this study. Platygaster oleae Szelenyi, 1940 (Platygasteridae) (30.2%) was the most common, Torymus phyllireae Ruschka, 1921 (Torymidae) (1.3%) was the least common species.