There are no significant differences in perception of pain produced by penetrations of 25-, 27-, and 30-gauge needles in the retromolar fossa. Six dentists received three series of six needle penetrations, three in each retromolar fossa, at one-week intervals. The penetrations were made to a depth of 2 to 3 mm with use of a rapid in-and-out motion by 25-, 27-, and 30-gauge needles in an alternating sequence. The perception of pain for each penetration was recorded, tabulated, and statistically analyzed. There were no significant differences in the perception of pain elicited from the use of the three needles.