Previous research documented intramuscular variations in the color and color stability of beef semimembranosus, which can be separated into color-labile inside (ISM) and color-stable outside (OSM) regions. Post-mortem aging is employed to improve beef quality attributes such as tenderness and palatability. Aging can also influence fresh beef color, whereas its effect on intramuscular color variations in beef semimembranosus is yet to be examined. Therefore, the objective of the present study was to evaluate the influence of aging on color and color stability of ISM and OSM and to examine if aging can mitigate intramuscular color variations. Semimembranosus muscles from 8 (n = 8) beef carcasses (USDA Choice, 24 h post-mortem) were vacuum packaged and aged at 2°C for 7, 14, and 21 d. On each aging period, muscles were fabricated into ISM and OSM steaks. Aerobically packaged steaks were stored in the dark at 2°C for 6 d. On d 6 of storage, lightness (L*), redness (a*), yellowness (b*), and color stability (ratio of reflectance at 630 nm and at 580 nm) were evaluated on the steak surfaces using a HunterLab LabScan XE colorimeter. The data were analyzed using PROC MIXED procedure in SAS. OSM exhibited greater (P < 0.05) surface redness (a* value) than ISM after 7 and 14 d of aging. However, after 21 d of aging, ISM and OSM demonstrated similar a* values (P > 0.05). While OSM was darker (P < 0.05; lower L* value) than ISM at all aging periods, there was no difference (P > 0.05) in yellowness throughout the aging. Color stability was greater (P < 0.05) in OSM than in ISM on d 7 and 21 of aging, whereas ISM and OSM exhibited similar (P > 0.05) color stability on d 14. These results suggested that 21 d aging could be employed to potentially minimize the intramuscular variation in redness of beef semimembranosus.