The purpose of this study was to gain further information about the behavioral effects of (+/-) 3.4-methylenedioxymethamphetamine (MDMA) on schedule-controlled responding. MDMA (0.32, 0.56, 1.0, 3.2, 5.6, and 10 mg/kg) and d-amphetamine (0.32, 0.56, 1.0, 3.2, 5.6, and 10 mg/kg) were administered to pigeons performing under a multiple fixed-ratio 30 (FR 30) interresponse-time-greater-than-15-s (IRT > 15-s) schedule of food delivery. In general, both drugs had no significant effect on response rates under the IRT > 15-s component at doses that decreased rates under the FR component. Results of the present experiment indicate that under some conditions MDMA and d-amphetamine produce similar, and rate-dependent, effects.