Background: Symptom scores and performance status are both important measures for patients with cancer. However, since performance status is not often part of routinely collected data, there is interest in exploring whether it can be calculated from symptom scores. Methods: This was a population-based longitudinal study of cancer outpatients in Ontario, Canada in the year following their cancer diagnosis and among the subset of patients during the last year of their lives. Results: In the first year after diagnosis, there was a significant relationship between performance status and fatigue and appetite; fatigue and well-being had a significant association with performance status in the last year of life. In both periods, the associations, although statistically significant, were not large enough to be clinically meaningful. Conclusion: Performance status is an important measurement that cannot be substituted or captured with symptom scores; it is important for healthcare providers to record performance scores on a regular basis.