Patients with relapsed low-grade follicular lymphomas (LGFL) frequently respond to subsequent therapy and can have long survival, but are rarely cured. Factors associated with complete remission (CR) rate, length of survival, and time to treatment failure (TTF) after relapse are not well known. We assessed such factors by multivariate analysis in a retrospective review of 95 patients with relapsed LGFL treated with investigational chemotherapy regimens at our institution. The CR rate after therapy was 22%; the likelihood of achieving CR was inversely associated with the number of previous treatment failures (P less than 0.001) and serum LDH level (P less than 0.05). Both the presence of constitutional symptoms and a history of more than two previous treatment failures were associated with shortened survival and TTF. Hemoglobin level was also significantly associated with survival. Prognostic models for survival and TTF were derived to define patient groups with different projected outcomes after therapy for relapsed disease. The results of this study can be used to select patients for new investigational treatments and to evaluate the outcome of such therapies.