Injectable poly-L-lactic acid (PLLA) is indicated in the United States for use in immune-competent patients for correction of shallow-to-deep nasolabial fold contour deficiencies and other facial wrinkles in which a deep dermal grid pattern injection technique is appropriate. It is also indicated for restoration and/or correction of signs of lipoatrophy in patients with human immunodeficiency virus. The authors examine the efficacy of injectable PLLA for correction of nasolabial fold wrinkles, based on Investigator Global Evaluations (IGE). A randomized, multicenter, subject-blinded, parallel-group study compared injectable PLLA versus human collagen for correction of nasolabial fold wrinkles for 13 months after up to four treatments (intent-to-treat population, 233). Injectable PLLA-treated subjects were followed up for an additional 12 months (total, 25 months) after the final treatment session. Efficacy was also assessed through secondary IGE for improvement, which is the subject of this report. IGE reports of improvement were significantly greater in subjects who received injectable PLLA versus those who received human collagen (p < .001). Overall improvement with injectable PLLA was 100% three weeks after the final treatment, remaining above 85% through month 25. Overall IGE of improvement with human collagen declined from 94.0% at week three to 6.0% at month 13. Both treatment groups had similar safety profiles. IGE of improvement were significantly greater with injectable PLLA treatment than with human collagen treatment at all time points following the last treatment. Injectable PLLA treatment continued to show a beneficial effect for up to 25 months.