Quantum field theories in front-form dynamics are not manifestly rotational
ly invariant. We study a model bound-state equation in 3+1 dimensional fron
t-form dynamics, which was shown earlier to reproduce the Bohr and hyperfin
e structure of positronium. We test this model with regard to its rotationa
l symmetry and find that rotational invariance is preserved to a high degre
e. Also, we find and quantify the expected dependence on the cut-off.