Identification of the normal fluctuations in body condition of equids is important for the monitoring and management of wild and feral equid populations. Knowledge of the causative factors and implications of body condition fluctuations may allow managers to better respond with interventions when body condition fluctuations are unseasonal or extreme. The body condition score (BCS) of 33 adult Przewalski's horses (22 mares and 12 harem stallions) roaming freely in a population in excess of 300 in the Hortobágy Puszta in Hungary was assessed weekly for 12 months from January to December 2009. Mares had a higher mean BCS than stallions for each month of the year, and all horses maintained a moderate to fleshy condition score. There were two peaks and two troughs in BCS for both mares and stallions. It appears that an annual fluctuation of body condition of Przewalski's horses is normal for horses living in a semiwild habitat. This can be explained by seasonal variation in pasture quality, an energy cost to mares in late gestation and early lactation, and a large energy cost to mares and stallions in protecting new born offspring from aggressive attacks by rival stallions and the work of band stallions protecting against challenging stallions. Although there was a seasonal fluctuation in body condition, semiwild horses living in a former wild horse habitat were never in poor condition. Managers of domestic, feral, and wild horses may tolerate a small reduction in body condition of horses during the annual seasonal cycle.