Occurrence of a secular trend in the presence of a common anatomical variant-median artery of the forearm is studied. Data from the literature indicated the incidence of the median artery to be between 4.4 and 8.3% in adult cadavers studied before 1960 while our recent study found a frequency of 27.2%. In 224 adult and 60 infant cadavers of people born between 1900 and 1991 studied using a uniform method the incidence of the median artery in the birth cohort 1900-1910 was 15.0% of individuals, it rose to 29.7% in 1921-1930 and further to 38.1% in 1951-1960 to become 52.8% in 1980-1991. This trend is statistically significant. Since the median artery is deemed to dwindle away in most individuals around the 7th week of the intrauterine life, the increasing proportion of individuals who retain it into postnatal life may indicate a recent trend in human intrauterine development.