This is a Phase 1, open-label, multicenter, extension study. Subjects with non-Hodgkin's lymphoma (NHL) (excluding chronic lymphocytic lymphoma [CLL], small lymphocytic lymphoma [SLL], and mantle cell lymphoma [MCL]) who completed a prior ABT-199 study, or were active and assigned to ABT-199 when the study was completed, may roll over into this extension study. Subjects will receive ABT-199 during this study.

Inclusion Criteria:

• Subject has completed a prior ABT-199 study (and had met the criteria for a diagnosis of NHL and all other eligibility criteria for the previous study) and the investigator believes that treatment with ABT-199 is in the best interest of the subject.

Exclusion Criteria:

• Subject discontinued ABT-199 administration before completing the prior study (due to disease progression, toxicity, withdrawn consent, other).
• Subject has any medical condition that in the opinion of the investigator places the subject at an unacceptably high risk for toxicities.
• Subject has not recovered to ≤ Grade 2 clinically significant adverse effect(s)/toxicity(ies) of previous therapy.
• Subject has been diagnosed with Post-Transplant Lymphoproliferative Disease (PTLD), Burkitt's lymphoma, Burkitt-like lymphoma, lymphoblastic lymphoma/leukemia, chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), or mantle cell lymphoma (MCL).