Objective:  This study investigates correlates of patient reported unhealthy days (unHD) in a Humana mostly Medicare cancer cohort undergoing chemotherapy.  Methods:  In 2015, surveys were mailed to 7,432 patients with metastatic breast, lung or colorectal cancer, > 1 comorbid conditions and treated for cancer within 3 months.   The Center for Disease Control and Prevention’s Healthy Days measure assessed self-reported unHD in the past 30 days.  Levels of cancer-related symptoms [pain, fatigue, shortness of breath (SB) and hair loss] in the past 30 days were reported on 5-point Likert scales.  Comorbidity Medication Adherence (CMA) was assessed using the 8-point Morisky Medication Adherence Scale and described as low (<6) or high (>=6).   Depression was identified in medical claims (ICD-9-CM 311).    Negative-binomial regression controlling for age, gender, Deyo-Charlson Comorbidity Index and cancer type was used to assess factors associated with unHD and was presented as rate ratios (95% confidence intervals).  Results:  The survey response rate was 25% (n=1,847).  67% of patients were female; 88% Medicare; mean age was 69.2+/-9.2.  In the multivariable models, patients with pain had 85% more unHD than patients without pain [1.85 (1.59-2.21); p=<0.0001]; patients with fatigue had 102% more unHD than patients without fatigue [2.02 (1.72-2.37); p=<0.0001]; patients with SB has 30% more unHD than those without SB, [1.30 (1.12-1.51); p=0.0005].   Patients with low CMA had 18% more unHD than those with high CMA [1.18 (1.01-1.39); p=0.0429].  Depressed patients had 18% more unHD than those without depression [1.18 (1.01 – 1.37; p=0.0384]. Those dually eligible for Medicare/Medicaid had 42% more unHD than those not dually eligible, [1.42 (1.05-1.92); p=0.0243]. Conclusion:  CMA, depression and Medicaid status were associated with patient-reported unHD.   Patient-reported cancer-related symptoms, most notably pain and fatigue, were most predictive of unhealthy days.  Interventions aimed at ameliorating these symptoms may improve quality of life for cancer patients.