As a series of systematic classification of paramphistomes, in the first step, paramphistomes in the rumen and reticulum were collected on 170 Korean cattles (2-3 years age, male) slaughtered at Jeonju abattoir from July 1984 to September 1985 and were classified by means of morphology of the worms. Afterwards, the karyotype of Paramphistomum explanatum (Creplin, 1849) which is the common in Korean cattle was detected by means of modified air-drying method from testis cells of the worm. The following is a brief summary of the leading facts gained through the experiment. Most of the cattle slaughtered at the abattoir were infected with paramphistomes. The 5 species of the worms were detected on 170 Korean cattle and the worm burden per head was from 2 to 784 (on the average 170) worms, 120(70.59 percent) heads out of them involving 2-100 worms. In 28,900 individuals of paramphistomes obtained on 170 Korean cattle, appearance rates of various worms were as follows : 49.74 percent in P. explanatum, 48.08 percent in P. cervi, 0.98 percent in Orthocoelium orthocoelium, 0.89 percent in Fischoederius cobboldi and 0.14 percent in Cotylophoron cotylophorum. The chromosome number of 620 P. explanatum in the haploid and diploid cells was n=9 and 2n=18, and abundant cells in meiotic division were observed; 1,420 haploid and 38 diploid cells were reliable. Nine pairs of mitotic chromosomes were homologous and the chromosomes were composed of five medium-sized metacentrics (m), subtelocentrics (st) or submetacentrics (sm)and four small-sized subtelocentrics (st) or submetacentrics (sm), while meiotic metaphase chromosomes were composed of five medium and four small-sized. The haploid of the testis cells showed C-band in the centromeric region from 8 of them, whereas the remaining chromosome No. 5 included heterochromatin on the tip region, and chromosomes No. 3 and No. 7 showed a remarkable C-band distinguished from other chromosomes.