The four stereoisomeric 2,4,6,8-tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxanes have been separated. Configurational assignments have been made to these compounds, and also to the two stereoisomeric 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxanes, and the meso and racemic 1,3-dimethyl-1,3-diphenyldisiloxanediols, on the basis of cyclisation experiments and n.m.r. spectroscopy. Gas chromatographic and infrared spectroscopic investigations are reported.