Abstract: The karyotype and Giemsa banding pattern of chromosomes of the gonadal cells of Ascaris lumbricoides and Ascaris suum collected from Guangzhou, were studied.The chromosome number of spermatogonial metaphase was 20 (2n = 20, n = 10) in Ascaris lumbricoides. The karyotype consisted of 2 pairs of larger medium-sized metacentrics, 5 pairs of medium-sized metacentrics, 1 pair of smaller medium-sized submetacentric and 2 pairs of small-sized telocentrics.The chromosome number of spermatogonial and oogonial metaphase were 20 (2n = 20, n=10) in Ascaris suum. The diploid metaphase plate in both cells consisted one pair of large-sized submetacentric or metacentric, six pairs of medium-sized meta centrics, one pair of small-sized submetacentric, two pairs of small-sized subtelocentrics or telocentrics. As shown in Fig. 1-4,the arrangement of chromosomes by size showed two karyotypes in A. lumbricoides and A. suum.