This study was designed to evaluate the dominant follicles development and the estradiol-17β concentrations in non-ovulating and ovulating post-partum buffaloes. Sixteen Bulgarian Murrah buffaloes were submitted to transrectal ultrasonographic examination from the 1st post-partum day until day 50, 3 days apart. The follicular diameter of the different categories of follicles and the ovulations was recorded. The animals were allocated into two groups: I (n = 6) non-ovulating and II (n = 10) ovulating buffaloes. Serum estradiol-17β concentrations on the days for dominant follicle registration were measured by enzyme-linked immunosorbent assay. The results were statistically processed by analysis of variance, non-parametric and correlation analysis. The mean intervals between calving and first dominant follicle detection differed significantly (p < .05) among the groups (19.5 ± 6.2 vs. 13.8 ± 5.1 days), while the mean intervals between registered dominant follicles from two successive waves were comparable. The mean follicular diameters for the same category follicles in both groups were similar. Different estradiol-17β concentrations (p < .05) for the first dominant follicle between non-ovulating (23.5 ± 7.0 pg/ml) and ovulating (33.3 ± 8.4 pg/ml) buffaloes were determined. The cumulative percentages of buffaloes with firstly detected dominant follicle and ovulating animals correlated positively (r ≥ .84; p < .05) to post-partum days. In conclusion, non-ovulating and ovulating post-partum Bulgarian Murrah buffaloes showed differences in the development of the first dominant follicle and estradiol-17β concentrations during the time of dominant follicles detection.