Genetic amniocenteses were performed in a series of 127 patients as a routine study. Samples from the patients were cultured by in situ method, flask method or both according to the state of amniotic fluid. The overall success rate of culture was 97.6% and no culture failure was observed in the flask method. It took 5 days first of all and 8.15 days average from set-up to harvest and there were 7.2 colonies per dish in in situ method. Therefore, it is suggested that in situ method which decreased the mean culture days and made clonal analyses possible, is a clinically available and even more reliable method in parallel with flask method in prenatal diagnosis.