This is multicenter, open label study to evaluate the safety and efficacy of bendamustine HCl in patients with indolent Non-hodgkin's lymphoma and relapsed after rituximab treatment. This injection will be given through i.v. infusion in >= 60 minutes on days 1 and 2 of every 21-day treatment cycle. Patients will be treated for up to 8 cycles unless progressive disease or unacceptable toxicity take place. Patients will be followed for up to 1 year before evaluating progression free survival (PFS) and overall survival (OS).