Abstract The crystal structures of the ternary phases (RE) 2(Ag, Al) 17 (RELa, Ce, Pr, Yb) contain puckered Kagomé nets of silver and aluminium which are stacked identically along the  direction. La 2Ag 17- x Al x ( x=7.3), Ce 2Ag 17- x Al x ( x=8.2), Pr 2Ag 17- x Al x ( x=7) and Yb 2Ag 17- x Al x ( x=8) crystallize as a ternary variant of the Th 2Zn 17 structure type (space group R3m; lattice constants in the range a=940.0–945.1 pm; c=1366.1–1372.7 pm; Z=3) which contains channels resulting from the sharing of common basal faces by hexagonal prisms of silver and aluminium atoms. Two-thirds of these prisms are occupied by RE atoms and one-third by Ag 2 pairs. La 1.8Ag 17- x Al x ( x=10.5), Ce 1.8Ag 17- x Al x ( x=10.5), Pr 1.8Ag 17- x Al x ( x=10.5) and Yb 1.8Ag 17- x Al x ( x=10) form ternary variants of the Th 2Ni 17 structure type (space group P6 3/ mmc; a=933.2–940.4 pm; c=911.0–915.3 pm; Z=3) with one-third of the channels being occupied by RE atoms and the remaining two-thirds alternately by Ag 2 pairs and RE atoms. A correlation between electron concentration and the various elements which occupy the hexagonal prismatic channels will be discussed.