Although digital examination is commonly used to assess anal sphincter tone and maximal squeeze pressure, the accuracy of this test has never been adequately validated. A total of 27 patients with a spectrum of subjectively assessed anal sphincter tones were studied. Simultaneous subjective (digital) and objective (manometric) determinations of maximal anal squeeze pressures were made. Subjective digital assessment revealed the following: three patients, absent squeeze pressure (grade 0); two patients, markedly reduced (grade +1); six patients, reduced (grade +2); and the remaining 16 patients had normal maximal squeeze pressure (grade +3). Simultaneous objective anal sphincter pressure measurements, when compared with these subjective values, revealed a correlation coefficient of 0.97 (p less than 0.05). Therefore, the clinician can reliably use the digital rectal examination to judge anal sphincter strength.