Twenty-four post-cardiac patients had 24 hour DER at a mean time of 30.1 days post-MI and 31.5 days post-MR. All patients experienced sexual activity at least once during the 24 hours. Heart rate ranged from a mean of 74.0 to 107.8 BPM in the MI group and from 90.2 to 117.8 in the MR group. Twelve of the 24 patients recorded cardiac electrical abnormalities during sexual activity and five of these 12 had abnormalities associated only with or more frequently with sexual activity. It is concluded that sexual activity may provoke cardiac electrical events not elicited by other stimuli and this may warrant consideration for patient counseling and/or specific therapy.