There have been numerous recent investigations of the possibility that laterality (the extent to which an individual is right or left-sided or, more usually, right- or left-handed), sexual orientation (homosexual, bisexual, or heterosexual), and immune system functioning are related. The reasons for inconsistencies in the literature and failures to reject the null hypothesis are discussed. Additional data are presented that show a positive relationship between left-sided laterality and homosexuality for a sample of HIV positive males. Immune system disorders were not associated with any of the other variables. It is concluded that increased left-sidedness is more likely in homosexual men as a group, but laterality cannot be used to differentiate homosexual men further into categories that vary in their susceptibility to immune disorders.