The presence of sperm subpopulations in domestic animals with known motility is well recognized [1]. In ejaculates of Holstein Friesian bulls it was observed the occurrence of four spermatozoa subpopulations with distinct motility patterns [2]. However, little attention has been given to the morphological characteristics of sperm, which can also determine different cell clusters. This study was aimed to morphometrically characterize sperm cells subpopulations in bulls using image analysis. Nine straws of frozen semen provided by artificial insemination centers, obtained from mature Bos taurus indicus bulls were studied. Samples were thawed in a water bath at 37 ° C for 30 seconds and fixed in phormol saline buffered solution. A light microscope (Olympus BX41) with green filter (Olympus IF550), coupled with a CCD camera (Charge Coupled Detector - SDC-415, Samsung) and connected to a microcomputer was used for image acquisition of 200 cells per bull in format ".bmp". The images were adjusted to 8 bits and then treated using the tools "Threshold" and "Wand (tracing) tool" of the software Image J ®, to measure area, perimeter, major and minor axes of the ellipse and center of mass of the sperm head. Statistical analysis was performed using the R software, and for each bull the clusters were identified considering the characteristics area, centroid, perimeter and center of mass of the sperm cells. It was observed three or four major cell clusters in ejaculates of different bulls. Among the nine bulls analyzed, five showed four major subpopulations, while the other four presented three subpopulations. Apparently there is not a unique parameter that characterizes a cell cluster, and therefore the morphological similarity of the cells is influenced by several morphometric features. Thus, different sperm cells subpopulations are present in Bos taurus indicus bulls ejaculates and they should be determined by image analysis techniques.