The Harris line (HL), caused by bone-growth arrest and manifesting on X-rays as a radiopaque transverse line in the metaphysis of the long bones, is an indicator reflecting stress conditions such as disease or malnutrition. HL frequency has been assumed to differ between pre-modern and modern societies, as reflective of increased caloric intake and overall nutritional improvements attendant on industrialization. To determine if such a change occurred in Korea, in the present study we compared the respective HL statuses in medieval Joseon and modern Korean population samples. HLs were found in 39.4% (28/71) of the Joseon Koreans. Whereas only 27.5% (11/40) of the males showed an HL, fully 54.8% (17/31) of the females exhibited it. Notably, HLs were observed in only 16.4% (35/213) of the modern Koreans; more remarkably still, the HL rate was almost the same between the sexes, 16.7% (20/120) for the males and 16.1% (15/93) for the females. The HL frequency was much higher in the Joseon Koreans than in their modern counterparts, reflecting the improvement of nutritional status that had been achieved in the course of South Korea's modernization. This HL-frequency decrease was much more obvious in the female populations. The higher HL frequency among the Joseon females might reflect the relatively poor nutritional condition of females in pre-modern Korean society.