Objective: Morphological indicators of chromosomal instability (CI), including multipolar mitoses, chromatin bridges (CB), strings, nuclear buds (NB), micronuclei (MN), and deoxyribonucleic acid (DNA) ploidy analysis help in prognostication of breast carcinoma. The present study was done to evaluate CI in breast carcinoma and correlate with DNA ploidy and tumor grade. Study Design: Fifty cases of carcinoma breast diagnosed by fine-needle aspiration cytology were included. Robinson’s grading method was used on smears to grade breast carcinoma. To assess the morphological features of CI, the best May-Grünwald Giemsa stained smear was chosen. At least 1,000 epithelial cells on oil immersion magnification (×100 objective) were counted. DNA ploidy on the aspirates was done by flow cytometry. Results: All the patients were female, diagnosed as infiltrating ductal carcinoma on cytology. Eight tumors were grade I, 32 were grade II, and 10 were grade III. MN was seen in 48 cases, NB in 45, and CB in 12 cases. Mean MN, NB, and CB scores in aneuploid (24) cases were 9.96 ± 8.42, 5.29 ± 4.71, and 1.08 ± 1.84 while 6.19 ± 6.67, 1.92 ± 1.79, and 0.11 ± 0.33 were seen in diploid (26) cases. Statistically significant positive correlation was observed between CI and DNA ploidy. Conclusions: Morphological evaluation of CI by light microscopy on routinely stained breast aspirates is feasible, although a meticulous search is required. Cytomorphological features of CI and ploidy have a positive correlation with increasing tumor grade.