In order to know the Body Condition evolution of dairy ewe flocks, forty flocks of Latxa ewe were studied during two productive years, from the end of milking period to the end of the following one. The Body Condition score (BCs) was stated monthly in 20% of the ewes older than 1 year, previously selected according to the age distribution of the flocks. In both years the average BCs was 2.5, with maximum values at the end of spring (May‑June) and minimum in January. These extreme values and the shape of the BCs reduction in the summer and autumn months, which is the period of mountain pastures utilisation, were influenced by effects like the year (p < 0,001) or ewe productivity (p < 0,001). These effects also influenced (p < 0,001) the reserves recovery in winter and spring months, during the milking period of flocks. A consequence of this evolution was a minimum BCs around lambing, even though the mobilisation during the last third of gestation was not important (a mean of 0,21 BCs units). This mobilisation was affected (p < 0,001) by the age, number of lambs born, lambing date or BCs of the ewe. The recovery of reserves along the milking period was also affected (p < 0,001) by the lambing date and milk production, by means of its effect on the beginning of the BCs recuperation. Using the BCs evolution of flocks as the clustering variable, each of the four clusters obtained was quite homogenous in mean lambing date and geographical location.