The allometry between baculum size, body size and body condition was studied in the polecat (Mustela putorius). The aim of this study was to investigate whether penis size is dependent on body size. We also calculated the correlation between the size of the baculum and body condition. Our research was based on 107 bacula and skulls from a museum in Slovakia. Individual traits describing the sizes of the body, skull and baculum were moderately to strongly correlated (r between 0.16 and 0.72). Condition was expressed as residuals from a regression analysis of body mass on structural body size. The size of the baculum was correlated with other measurements of body size and with body mass. Analysis revealed that the strongest positive correlation with condition of males was with the size of the baculum. Because the baculum varies between individuals and grows throughout life, the relationship between its size and condition confirms that the baculum may be a suitable indicator of male quality.