In order to assess the extent of xylazine (Xyz) injection in Puerto Rico, two waves of used-syringe collections were performed. In the first, syringes were gathered, anonymously and without additional information; in the second, a short interview, also anonymous, was administered. We found Xyz in 37.6% of the collected syringes; the majority of the Xyz-containing syringes came from ranching communities. Syringes containing Xyz more frequently also contained "speedball" than those without (90.6% and 66.7%, respectively). Self-reports of Xyz injection deviated markedly from actual detection: only 50% (self-described users) and 22% (self-described non-users) of the collected syringes contained the drug. With a high prevalence of skin ulcers (38.5% vs. 6.8%; p<0.001), Xyz users were more likely to be in poor health compared to non-users. Surprisingly, though a higher percentage of Xyz users than non-users had college-level educations (23.1% vs. 5.5%), they were more likely to be homeless (64.1% vs. 37%).