Somatic chromosomes were studied from roots from seven species and two varieties of the genus Opuntia collected from different localities in Eastern India. 2n = 22 chromosomes were observed in four, 2n = 44 in two and 2n = 55 chromosomes in one population. The total chromosome length is maximum in O. Ficus-indica (2n = 55) and minimum in O. microdasys var. lutea (2n = 22). The karyotypes show a similarity in basic number x = 11, except for the horticultural variety, O. monocantha variegata with 2n = 34. The chromosome sizes range from very small (0.97 mm) to medium (3.46 mm); the primary constriction varies from nearly submedian to median and the numbers of chromosomes with secondary constrictions are from four to six. Numerical analysis of data indicates a general similarity of the karyotypes, with O. Ficus-indica occupying a separate position. © 2000 Taylor & Francis Group, LLC.