NMR analysis of adamantane and four bicycloalkanes substituted at the bridgehead with l5N-labeled amino and ammonio groups is described. It is found that where most of the one-bond carbon-nitrogen coupling constants are relatively large, those in l-aminobicyclo[1.1.1] pentane and its hydrochloride are significantly reduced; in fact, in the latter compound one-bond 13C-15N coupling could not even be detected. Values of experimentally determined vicinal couplings were in accord with those expected on the basis of the number of three-bond pathways available for transmission of spin-spin information; INDO calculations, however, suggest that in the more highly strained systems there is a substantial contribution to3J(CN) arising from through-space interactions and that these oppose through-bond effects. Large four-bond 15N-1H couplings were found to occur in l-aminobicyclo[1.1.1]pentane and its hydrochloride; MO calculations indicate that through-space interactions constitute the predominant mechanism contributing to 4J(15N-1H), although in this case through-bond and through-space effects reinforce each other. The nitrogen-15 chemical shifts of the amine hydrochlorides were determined, and they appear to occur in random fashion.