Magnetic properties of ternary RPtSn (R = Ce, To, Ho) compounds are de
termined. Ail compounds are antiferromagnets with T-N = 8 K (CePtSn),
13.8 K (TbPtSn) and 9.2 K (HoPtSn). All compounds have a sine modulate
d magnetic structure. In the case of TbPtSn and HoPtSn, changes of mag
netic structures are observed at T-t = 10 K and at T-t = 3 K respectiv
ely.