Study of sexual differences for the hemispheric prevalence on visual verbal stimuli using a microcomputer-based tachistoscope technic. Seventeen right-handed individuals, 10 males and 7 females (mean age 32 years old), without neurological or visual abnormalities were studied. The subjects performed a verbal trigram tachistoscope test, using a IBM PC microcomputer compatible. The trigram consists of 80 consonant-vowel-consonant pairs of stimuli presented randomly to right and left visual fields. The evaluation was made through two conditions: T1 and T2. In T1 Experiment stimuli exposition time was 260 ms, and in T2 Experiment the stimuli exposition time was 160 ms. In Tl Experiment 80% of females showed a Right Hemispherical Preference while 100% of males showed a Left Hemispherical Preference. In T2 Experiment, both sexes showed Left Hemispheric Preference. A close relationship between sexual difference and hemispheric preference was found. We point out the importance of stimuli exposition time in determination of sexual differences in lateral hemispherical asymmetry.