SUMMARY: This is a multi-center open label study to evaluate the safety and effectiveness of Treanda™ (also known as bendamustine HCl or SDX-105) in patients who have indolent Non-Hodgkin's lymphoma and have relapsed within a defined timeframe after taking rituximab (Rituxan®). Treanda will be given via 60-minute intravenous infusion on days 1 and 2 of every 21-day treatment cycle. Patients will be treated for 6 cycles unless they develop progressive disease or unacceptable toxicity. Those who continue to receive clinical benefit at end of 6 cycles may receive an additional 2 cycles. Following the end of treatment, patients will be followed for up to 2 years until disease progression or start of another anti-cancer therapy.