This study investigated the cause of clumsiness in two university students whose school achievements were normal but whose movements were remarkably clumsy. The students were selected from PE classes of university. Test items consisted of physique and fitness test items, some familiar motor tasks, and some motor learning tasks. Some perception tests and perceptual development tests were also given to the subjects to check for perceptual disorders, and their personalities were investigated in relation to their low motor abilities using personality inventories including interview survey for growth history. To obtain standard values for certain tasks which have no age-related standards, twenty male students were used as control subiects and the same items were evaluated. The results in the two subjects are presented as a percent and a Z-score against the standard value (Table 2-3), and their differences were discussed in relation to the scores. The physique of one subject was larger than Japanese standard, while the height of the other was average but his build was somewhat slight. Width scores were relatively smaller than their height scores except skinfold at the abdominal. This indicates that the subjects were slim. All the muscle strength scores were below the standard even for the taller subject. Jump movements were scored at less than thirty in Z-score and the Z-scores for more complex movements such as throwing were about twenty. Reaction times were also more than one SD greater than the standard. Performance of the motor tasks were far lower than the average except for a few items. Learning experiments, however, showed that these students had some learning ability. Adaptability to speed change and gross-motor-skills seemed to be the biggest problem for both students. Visual recognition tests did not show clear deficiency, however, two-points threshold on skin could not be measured because of their inability to distinguish the sensation of "two points" from that of "one point". Interviews revealed that these subjects were clumsy from childhood, but were never bothered by the clumsiness. As children, they liked to play alone. The personality test revealed that their scores for depression, neurosis, and self-exhibition were low. Extreme clumsiness did not seem to cause mental instability. Therefore, it was speculated that these students accepted the situation and did not push themselves to improve their motor skills nevertheless they were clumsy. The present state of clumsiness would becaused in part by their inherent disability, but another part was caused by less practice because of their personality and by inadequate guidance from their teachers.