The problems associated with the subjective assessment of human sperm morphology have been well aired in another Asian Journal of Andrology Special Issue1 that marked the publication of the 5th edition of the WHO Semen analysis manual,and contrary views have subsequently been presented.2 However,the vagaries of the eye-brain system in assessing whether a sperm head is large or small can be eliminated by objective assessment where definitive structures are defined by their dimensions.These can then be classified automatically into as many categories as the data permit,conventionally on the basis of preset upper and lower limits,but also by more comprehensive analysis as discussed here.