Eight adult male research volunteers received cocaine and marijuana, alone and in combination during experimental sessions. Following the determination of baseline cardiovascular indexes, a one-gram marijuana cigarette (0-2.9% delta 9-THC w/w) was smoked, and cocaine hydrochloride (4-96 mg) was inhaled five minutes after completion of marijuana smoking. Subjects performed a learning task 25 and 70 minutes after initiating marijuana smoking. Cocaine increased heart rate, which averaged 68 bpm under resting baseline conditions, by up to 15 bpm, marijuana increased heart rate by up to 27 bpm, and task performance increased heart rate by 5 bpm. The combination of cocaine and marijuana produced increases in heart rate that were similar to those seen with marijuana alone. During task performance in combination with cocaine and marijuana administration, however, heart rate was elevated by 37 bpm. Although more variable, the largest increases in blood pressure were observed following combinations of cocaine, marijuana, and task performance. These findings suggest that the self-administration of cocaine and marijuana under nonresting conditions has greater cardiovascular effects than the self-administration of these drugs under resting conditions.