Genetic variation at twenty simple sequence repeat (SSR) markers loci was used to evaluate 21 Tanzanian farmerpreferred cassava landraces collected and maintained at Mikocheni Agricultural Research Institute laboratory in Tanzania.Two West African cassava genotypes and one Kenyan cassava were included in the clustering analysis. Genotyping with twenty high polymorphic SSR markers grouped the genotypes into three clusters derived from Neighbour joining analysis. Clustering analysis was well supported by principle component analysis (PCA). The first three axes of PCA with positive Eigen values accounted for 22.76, 15.93 and 8.48 % of the total variations respectively. No genotype duplicates were detected among the cassava landraces. Average gene diversity among the Tanzanian cassava was high (0.71) with an average heterozygozity of 0.46. Total number of alleles across all loci was 127 with mean number of alleles per locus being 6.35 and SSR markers had a mean polymorphic information content of 0.67. The results obtained in this study facilitated on selection of genotypes to include in the ongoing cassava genetic improvement programs in Tanzania and germplasm conservation.