Five larval diets for laboratory rearing of Bactrocera oleae Gmelin were tested. These diets were based on soy hydrolysate, yeast, sugar, casein, wheat germ, microcellulose and agar. The quality of diets was evaluated by measuring larval and pupal survival, larval and pupal weights, and development times. The best results were obtained with an agar-based diet that was modified from the currently used cellulose-based diet for rearing olive fruit fly in mass rearing facilities. Under these conditions, 77% of the larvae reared on the new agar-based diet completed development and achieved higher pupal weight than larvae reared on the currently available cellulose diet. The average life cycle was completed in 25.2 +/- 0.4 d on the agar diet, and other biological parameters were also very close to those on the cellulose diet. Olive fruit fly larvae were reared continuously and successfully for 4 generations on the new diet. The preparation of the new agar-based diet is simple, the cost is low, and it is useful for small-scale laboratory tests and rearing.