We report a case of severe hyponatremia following hysteroscopic myomectomy for uterine fibroids. This new technique, which requires large volumes of irrigation solution (1.5% glycine in this case), is being more widely applied as an alternative to open surgery. Thus, nephrologists may expect to encounter such cases as the female counterpart to transurethral resection of prostate-associated hyponatremia. Analysis of the dynamic features of this case, in the context of recent knowledge of glycine metabolism, suggests that the early severe hyponatremia is partly spurious, reflecting an osmotic effect of glycine (which is initially restricted to the extracellular space). As glycine progressively enters cells and is metabolized, the later phase of hyponatremia more accurately reflects true hypo-osmolality.