How long is the individualized training and the stability of competence for the embryo transfer (ET) technique? The embryo transfer technique is easy-to-learn, hardly unlearned, and training should be individualized by monitoring with learning curve-cumulative summation (LC-CUSUM) curves. Like many medical procedures, embryo transfer is an operator-dependent technique. Individualized or standardized training of these medical procedures should be monitored to determine when competence is acquired. This prospective, monocentric study involving five embryo transfer trainees was carried out between August 2011 and November 2012. The study was carried out in a large private clinic. Five gynaecologist trainees during their first year of assisted reproduction subspecialty performed embryo transfer for patients undergoing either fresh IVF, oocyte donor IVF, or frozen embryo transfer. There were 586 embryo transfers performed in 96 sessions of 3-10 embryo transfers each. An embryo transfer was considered successful if it gave rise to a positive pregnancy test 14 days later. LC-CUSUM and cumulative summation (CUSUM) curves were used to determine when competence was acquired and whether it was maintained over time, respectively. The length of time between two consecutive sessions was assessed for an effect on consolidation of the acquired competence. We observed that all five trainees became proficient in embryo transfer by procedure 15 (after procedure 15, 9, 7, 13 and 9, respectively). Once competence was achieved, one of the five trainees showed a loss of proficiency. After having acquired competence, the median pregnancy rate per embryo transfer session was significantly lower when the interval between consecutive embryo transfer sessions was ≥10 days compared with <10 days (20.0 versus 46.7%; P = 0.006). The patient groups included in the study were heterogeneous (IVF, oocyte donor IVF and frozen embryo transfer) and their outcomes are very variable; thus the distribution and proportion of these groups can determine the timing of competence acquisition. Our data show that low numbers of embryo transfer are needed to acquire competence, but since a relative high percentage of embryo transfers in our practice are from oocyte donor IVF, extrapolation of the findings to other clinical context should be done with caution. Personalized embryo transfer training is feasible and useful, allowing clinics, on one hand, to offer a maximum chances of pregnancy with fully trained personnel, and the other hand, to avoid the superfluous and costly overtraining of already proficient trainees. Furthermore, it is advisable to maintain a short interval of time between consecutive embryo transfer sessions after a trainee has acquired competence, to avoid a significant drop in the resulting pregnancy rate. This work was supported in part by funding from Fundació Privada EUGIN. There are no conflicts of interest to declare.