The objective of the present study was to characterize under low altitude colombian tropical conditions the fol- licular dynamic pattems in six Gir breed heifers through- out an estral cycle, using the ovary ultrasonic imaging with identification and non identification methods. An equal proportion in the exhibition of cycles of two or three waves of follicular development was observed in all six heifers. Two wave heifers (n=3) showed a signifi- cant difference (P 0.05) between the length of the first wave, ten days and the second, nine days were observed. In the three wave heifers (n=3) there were significant differences (P<0 .05) in the day of maximum diameter of dominant follicle, 4.66 for the first wave, 12.33 for the second and 20.33 for the third one. The day of maximum diameter of the subordinated follicle was 2.66 for the first wave, 11.33 for the second and 18.66 for the third. No differences (P>0.05) between the waves length, 8.6 for the first and the second wave and 7.6 for the third was observed. In four of the six heifers the ovulation appeared in the left ovary.