The effects of sniffing different concentrations of the human sex-steroid derived compound 4,16-androstadien-3-one (AND) on autonomic nervous system function and mood were measured in 60 subjects. The effects were sex-specific and concentration-dependent. Only high concentrations of AND (0.00625 M) increased positive mood (p < 0.03) and decreased negative mood (p < 0.05) in women compared to men, and had sympathetic-like effects in women (p < 0.003), and parasympathetic-like effects in men (p < 0.05). These findings further implicate AND in chemical communication between humans, but pose questions as to the path by which AND is transduced, whether through chemical sensing or transdermal diffusion.