In extending a previous study the medial part of the frontal lobe of squirrel monkey was explored with respect to positive loci for penile erection. Strongly positive loci were found in precallosal cingulate gyrus and subcallosal region and in caudal part of gyrus rectus. Optimum stimulus parameters were moderately long pulses (1 msec) applied at a frequency of 20–30/sec. Mean latency of response was 4.9 sec for the precallosal cingulate region and 5.0 sec for the subcallosal region and gyrus rectus. Stimulation at positive loci evoked potential changes in the hippocampus. With pregenual cingulate stimulation a correlation was found between the appearance of erection and the recruitment of high-voltage slow hippocampal potentials. Associated behavioral effects included urination, cardiac slowing, respiratory acceleration, vocal changes, defecation, and salivation. Urination and cardiac slowing were the most frequent, with a respective incidence of 40 and 20%. Stimulation in ventral part of frontal lobe resulted in sneezing, head shaking, licking, chewing, and cardiac changes which might be associated with hippocampal evoked potentials and afterdischarges when electrodes were in or near olfactory bulb and tract. The findings are discussed in relation to preceding studies.