  Let 0<\theta<\pi such that \cos\theta\in \Q. In this paper, we prove that for
given positive square-free coprime integers k,l, there exist infinitely many
pairs (M,N) of \theta-congruent numbers such that lN=kM. This generalize the
previous result of Rajan and Ramaroson [A. Rajan and F. Ramaroson, Ratios of
congruent numbers, Acta Arithemetica 128 (2007), no. 2, 101-106] on the ratio
of congruent numbers from congruent numbers (i.e. \theta=\pi/2) to arbitrary
\theta-congruent numbers.
