It is now well established that genes within the major histocompatibility
complex (MHC) somehow affect the production of body odors in several vertebrates,
including humans. Here we discuss whether variation in the intensity of body odors
may be influenced by the MHC. In order to examine this question, we have to control
for MHC-linked odor perception on the smeller's side. Such a control is necessary
because the perception of pleasantness and intensity seem to be confounded, and the
causalities are still unsolved. It has previously been found that intense odors are
scored as less pleasant if the signaler and the receiver are of MHC-dissimilar type, but
not if they are of MHC similar type. We argue, and first data suggest, that an effect of
the degree of MHC-heterozygosity and odor intensity is likely (MHC-homozygotes
may normally smell more intense), while there is currently no strong argument for
other possible links between the MHC and body odor intensity.