We compared two methods of collection of transcervical cell samples, mucus aspiration and cytobrush, with respect to the efficiency in determining fetal sex and we correlated the results with the week of gestation (7-11 weeks) to evaluate if the age of gestation influenced the success of the analysis. DNA extracted from TCC samples recovered by mucus aspiration (n = 27) and cytobrush (n = 36) were analysed by nested PCR to predict fetal sex. The statistical indices of sensitivity, specificity, positive predictive value and negative predictive value were determined, and compared with those of other studies previously performed. No statistically significant difference was found between the two methods of TCC sampling concerning the success of fetal sex prediction which was high for both methods (78 per cent and 89 per cent) and no correlation with the week of gestation was found. Transcervical cell sampling represents an encouraging prospect for first-trimester prenatal diagnosis even when the least invasive techniques are used.