Provider-initiated HIV testing and counseling (PITC) has expanded since 2007 WHO guidelines were established. We conducted a systematic review of PITC in low- and middle-income countries. Peer-reviewed studies were included if they measured pre-post or multi-arm outcomes. Two coders abstracted data using standardized forms. Nineteen studies were included, all from sub-Saharan Africa (N = 15) or Asia (N = 4). Studies were conducted in clinics for antenatal/family planning/child health (N = 12), tuberculosis (N = 4), outpatient (N = 1), sexually transmitted diseases (N = 1), and methadone maintenance (N = 1). HIV testing uptake increased after PITC. Condom use also increased following PITC in most studies; nevirapine uptake and other outcomes were mixed. Few negative outcomes were identified. Findings support PITC as an important intervention to increase HIV testing. PITC's impact on other outcomes is mixed, but does not appear to be worse than voluntary counseling and testing. PITC should continue to be expanded and rigorously evaluated across settings and outcomes.