This is a six-week, randomized, double blind, multi-center, parallel group Extension to the BL-1020 IIb study. In this Extension Study in patients hospitalized with schizophrenia who were previously treated in the BL-1020 IIb study with BL-1020 (low dose: 10 mg/day; high dose: target dose 30 mg/day), risperidone (target dose: 8 mg/day) or placebo after experiencing an acute exacerbation of schizophrenia. Patients who completed the 6 week treatment period and/or all efficacy assessments in Study BL-1020 IIb are eligible to continue double-blind treatment in this optional 6 week Extension Study. Approximately 220 patients will be enrolled in this study: Treatment Group IE (n=82, 10 mg/day BL-1020); Treatment Group IIE (n=82: target dose 30 mg/day BL-1020); Treatment Group IIIE (n=55; target dose 8 mg/day risperidone). Study drug (BL-1020 or risperidone) will be administered orally, once daily, in a doubleblinded manner, during this six-week Extension Study