The in situ rhodium-catalyzed addition of catecholborane (HBcat, cat = 1,2-O₂C₆H₄) and pinacolborane (HBpin, pin = 1,2-O₂C₂Me₄) to allylamine, allylimine, 2- and 4-vinylpyridines, and a thienyl imine has been examined using multinuclear NMR spectroscopy. Although reactions of allylamine (H₂NCH₂CH=CH₂) and HBcat gave complex product distributions arising from competing dehydrogenative borylation pathways, addition of HBpin to allylamine using a rhodium catalyst afforded only products arising from hydroboration (RN(Bpin)CH₂CH₂CH₂Bpin, where R = H, Bpin) and hydrogenation (RN(Bpin)CH₂CH₂CH₃). Hydroboration of allylimines (RHC=NCH₂CH=CH₂, R = Ar) with HBcat occurs initially at the more reactive imine functionality to give unsaturated borylamines (RCH₂N(Bcat)CH₂CH=CH₂). Further reaction with HBcat gives varying amounts of hydroboration products RCH₂N(Bcat)CH₂CH₂CH₂Bcat and RCH₂N(Bcat)CH₂CH(Bcat)CH₃ as well as the diboration product RCH₂N(Bcat)CH₂CH₂CH(Bcat)₂, depending on the choice of catalyst. Reactions with related unsaturated pyridine derivatives are complicated by extensive degradation, which can be avoided by coordination of the pyridine nitrogen to a Lewis acid. The first examples of metal-catalyzed hydroboration of imines using HBpin are also reported.Key words: catalysis, hydroboration, boronate esters, dehydrogenative borylation, allylimines.