The infrared spectra (3200 to 600 cm(-1)) of gaseous vinylarsine and vinylstibine and their As-dideuterated and Sb-dideuterated derivative were recorded at 1 cm(-1) resolution. Both the infrared absorption bands of the syn and gauche conformers of the vinylarsine and vinylstibine were observed and assigned. The integrated intensities of isolated and overlapping vibrational bands were determined experimentally. Density functional theory calculations at the B3LYP/6-311G(d) level were performed to obtain the values of the harmonic vibrational frequencies. The results obtained are in good agreement with the experimental spectra and help in the assignment of the vibrational bands within the complex absorption region between 1100 and 600 cm(-1).