The Mediterranean fruit fly, Ceratitis capitata Wiedemann, represents an extremely harmful insect pest of considerable agricultural and economic interest. As part of the study of this species, two diploid cell lines (2n = 12) of the Med-fly were established in vitro on two different culture media. The two lines were obtained from embryonic eggs 24 (+/- 1) hours old and were called CEC CC 128 and CEC CC 130. Detailed descriptions are given of the techniques used for the preparation of the primary cultures, their development and characterization, the choice and composition of the culture media and the intrinsic characteristics of the lines obtained. Indications of other elements are given, such as different cells, non cellular vesicles and glands containing symbiotic bacteria, observable in the first phase of development of the culture, before obtaining continuously growing cell lines. The doubling time of the population for both cell lines were estimated at 22 hours and the interval between successive sub-cultures at 7 days.