Previous research had indicated that the judged familiarity (f) of verbal stimuli is some monotonic function of their objective frequencies of occurrence (n). In order to determine the exact form of this relationship, a sample of 16 words initially low in f value was presented randomly to 288 Ss in in the following frequencies: 0, 1, 2, 3, 4, 5, 10, 15, 20, 25. Each item was pronounced aloud as it occurred. Subsequently, Ss evaluated each word for familiarity on a five-point graphic rating schedule. These data were transformed to equal interval f values, then adjusted for pre-exptl. familiarity. When the adjusted f values were plotted as a function of N, a hyperbolic function resulted. Rival interpretations of this empirical familiarity-frequency relationship were discussed.