To investigate prevalence and severity of symptoms and symptom clustering in breast cancer survivors who attended MBSR(BC). Women were randomly assigned into MBSR(BC) or Usual Care (UC). Eligible women were ≥ 21 years, had been diagnosed with breast cancer and completed treatment within 18 months of enrollment. Symptoms and interference with daily living were measured pre- and post-MBSR(BC) using the M.D. Anderson Symptom Inventory. Symptoms were reported as highly prevalent but severity was low. Fatigue was the most frequently reported and severe symptom among groups. Symptoms clustered into 3 groups and improved in both groups. At baseline, both MBSR(BC) and the control groups showed similar mean symptom severity and interference; however, after the 6-week post-intervention, the MBSR(BC) group showed statistically-significant reduction for fatigue and disturbed sleep (P<0.01) and improved symptom interference items, compared to the control group. For the between-group comparisons, 11 of 13 symptoms and 5 of 6 interference items had lower means in the MBSR(BC) condition than the control condition. These results suggest that MBSR(BC) modestly decreases fatigue and sleep disturbances, but has a greater effect on the degree to which symptoms interfere with many facets of life. Although these results are preliminary, MBSR intervention post-treatment may effectively reduce fatigue and related interference in QOL of breast cancer survivors. © Springer Science+Business Media, LLC 2011.