The effect of age upon the subjective magnitude of line length was assessed by the method of absolute magnitude estimation in three groups of subjects with mean ages of 25, 50, and 68 years. The results showed no significant differences between the groups. When compared to data from an earlier study in which 5- to 6-year-old children were tested by the same method, the results were essentially the same, but with a slightly steeper slope for the 5- to 6-year-olds. The subjective length of lines appears to remain stable over an extended age range.