It is with great interest that we have read the paper published in your journal by Kerimoglu et al. [1] which addresses an important clinical question: the decrease of daily administered Cetrorelix dose in controlled ovarian hyperstimulation (COH) cycles to avoid premature LH surge while improving pregnancy rates mainly by the subsequent modifications at a cellular level. However, the article reports somewhat precipitate ‘conclusions’, which have the potential for misinterpretation and are in contrast, in several ways, with some important studies published in the past (see Table 1). Firstly, a ‘dose-finding’ study cannot be, by definition, ‘‘retrospective’’. Therefore, it is premature to state that ‘there is no difference...’ between the two regimens, as there have been studies in the past (even referred in Kerimoglu’s et al. [1]), with a prospective and, sometimes, even with a randomized design that clearly state that the lowest daily effective dosage for pituitary down-regulation with Cetrorelix is 0.25 mg/day. Furthermore, in an important—because of its design— randomized controlled trial (RCT) (not mentioned in Kerimoglu’s et al. [1]), Chang and colleagues [2] compared efficacy and efficiency of Cetrorelix and found to be 0.2 and 0.15 mg, respectively; they concluded that even for Asian women (for whom BMI is known to be lower than the Caucasian population), the lowest daily dose of Cetrorelix (in achieving satisfactory pituitary down-regulation) was 0.2 mg, and thus stated that daily administration of 0.15 mg ‘is not suitable’ for pituitary down-regulation. In addition to this, Chen et al. [3] also suggest that for Asian population ‘the lowest effective daily dosage is that of 0.2 mg’ and not 0.25 mg; even if one disregards the design of the study (non-randomized observational), that dose is closer to the ‘established’ one (0.25 mg) than the dosage of 0.125 mg suggested by Kerimoglu et al. [1]. Closely related to this are the findings of a more recent and larger retrospective study by Hsieh et al. [4]. That study concludes that ‘even for individuals with lower body weight (\50 kg), participants required 0.25 mg Cetrorelix daily. Furthermore, Tzeng’s study protocol [5], mentioned in Kerimoglu’s et al. [1], is quite different from daily Cetrorelix administration of 0.125 mg as it depends on leading follicular size; however, even with that protocol, the mechanism for LH-surge avoidance (which is used in 3 patients to end with the one LH surge that is mentioned in the paper) was the increase of the Cetrorelix dose to 0.25 mg/day. Finally, we should acknowledge the (potential) first ‘dose-finding’ study by Albano et al. [6], which concluded that ‘the minimal effective dose of Cetrorelix’ to prevent premature LH surge is 0.25 mg/daily. If a decrease in dosage is to be considered, further larger RCTs need to be conducted before we can move with confidence, to change in current clinical practice. T. Kalampokas Division of Applied Health Sciences, Assisted Reproduction Unit, University of Aberdeen, Aberdeen, UK