Nocturnal penile tumescence and rigidity data were collected during 3 successive nights of home monitoring from 44 men screened for normal sexual functioning. The subjects were well distributed during the interval with an age of 31 to 81 years. Penile brachial indexes, biothesiometry measures and testosterone levels were evaluated. Two new time-intensity measures of tumescence (tumescence activity units) and rigidity (rigidity activity units) were used to summarize erectile activity. A high correlation (r > 0.84, p < 0.001) was found between these summary parameters. It was observed that at least 2 nights of monitoring were required to characterize a subject adequately because some men had single nights with no measurable erectile activity. There were low correlations among penile brachial index, biothesiometry and testosterone outcomes, and nocturnal penile tumescence and rigidity measurements. There was a decrease in measurements of tip rigidity with increasing subject age (r = -0.238, p < 0.05) and an increase in tip rigidity associated with penile girth during erectile events (r = 0.505, p < 0.001). Cumulative distributions of rigidity and tumescence activity units were developed to permit a simple, direct comparison of other nocturnal penile tumescence and rigidity findings to results in the study population.