Results of the karyomorphological investigations of five species with their different races of the genus Ocimum included in the Sanctum group are described. Comparative cytological study reveals that the length of chromosomes and gross appearance of the karyotype show a general resemblance in all the species investigated but upon closer examination the karyotypes, however, show a wide range of variation in chromosome number as well as in the type of chromosomes. The difference in the karyotype of different species is mainly due to the difference in their chromosome number as well as in the type of chromosomes. The difference in the karyotype of different species is mainly due to the difference in their chromosome number as well as the difference in the number of chromosome type belonging to the different group. The present study also suggests to presume the existence of at least four base numbers x=8, 10, 12 and 16 because of a wide range of chromosome numbers present in the Sanctum group.