We deal with the existence of quasi-periodic Solutions of forced isochronous oscillators with a repulsive singularity, the nonlinearity is a bounded perturbation. Using a variant of Moser's twist theorem of invariant curves, due to Ortega [R. Ortega, Boundedness in a piecewise linear oscillator and a variant of the small twist theorem, Proc. London Math. Soc. 79 (1999) 381-413], we show that there are Many quasi-periodic Solutions and the boundedness of all Solutions. (C) 2009 Elsevier Inc. All rights reserved.