A survey of the multimolecular inclusion compounds formed bysyn-2,syn-7-dihydroxy-2,7-dimethyltricyclo[4.3.1.13,8]undecane1 and 34 guest molecules shows that two inclusion crystal structures are commonly obtained, namely the helical tubulate inclusion lattice and the ellipsoidal clathrate structure type. Interactions between host and guest are necessarily weak since the host surface is hydrocarbon. Small differences in the guest molecules can tip the balance between alternative inclusion lattices, one of which is chiral. For the first time precise guest locations in the helical tubulate structure have been obtained by X-ray diffraction analysis. Crystal data:1·CCl4: space groupP3121,a=13.2812(2),c=6.904(1) A, unit cell contents 3(C13H22O2) + 1.2CCl4,R=0.044;1·BrCH2CH2CH2Br: space groupP3121,a=13.206(2),c=6.915(2) A, unit cell contents 3(C13H22O2)+ BrCH2CH2CH2Br,R=0.042;1.0- xylene: space groupP3121,a=13.380(2),c=6.905(1) A, unit cell contents 3(C13H22O2) + 1.2 C8H10,R=0.042.