Five cases infected with Rhabditis sp. were detected in a survey to examine the stool specimens from rural primary school children. A large number of the larvae of Rhabditis sp. detected by the direct cellophane thick smear were cultured by the alter paper method. The eBamination was carried out in April through June, 1980 in Tangjeong-Myon, Ahsan.Gun, and in September 1983 in Sandong-Eup, Yeongwol-Gun. The results obtained in this study were as follows: 1. Prevalence: Out of 925 children, 5(0.54%) children were found to be positive. The number of the detected larvae was 110/0.1gm of feces in case 1, 35 in case 2, 130 in case 3, 86 in case 4 and 62 in case 5. 2. Larvae: The larvae were prepared by means of the direct fecal smear and measured by a micrometer equipped in the microscope. Twelve (12) through 15-day old larvae in culture were $197.1{mu}{ extrm{m}}$ long in average, and the maximum size of the matured stage larvae was $884.0{ imes}25.9{mu}{ extrm{m}}$. However, the length variation was ranged as 173.0 to $884.0{mu}{ extrm{m}}$. 3. Adults: The size of clubbed adult female was $1, 357{mu}{ extrm{m}}(1, 176~1, 419)$ in length and $80{mu}{ extrm{m}}(79~82)$ in width. Length of buccal cavity was $33{mu}{ extrm{m}}$. A long cylindrical esophagus($273{mu}{ extrm{m}}$) of the worms with a valved posterior cardiac bulb and with median bulbar swelling was morphologically indicated. Ditance from mouth to vulva was occupied 58% of body length. Male worm was $1, 006{mu}{ extrm{m}}(890~1, 148)$ in length and $49{mu}{ extrm{m}}(48~49)$ wide. Caudal alee of bursa and spicules ($75{mu}{ extrm{m}}$ in length) were well developed. 4. Eggs: The oval shaped eggs in the female uterus, when cultured, were $66{ imes}56{mu}{ extrm{m}}$ in sixte, and the eggs laid by the adult could not be detected. So, reproduction might be thought to be ovoviviparity. 5. The five cases were re-examined during the period from the 1st to the 3rd week after stool examinations, but Rhabditis sp. were detected again in 4 cases in 1st week. When they were examined in 3rd week, larvae could not be detected. So, it was thought that the infection of Rhabditis sp. to humans was facultative.