Many ostomy patients experience peristomal skin lesions. A descriptive study was conducted to assess the validity, usability, and reliability of the Peristomal Skin Lesions Assessment instrument (SACS instrument) adapted to Turkish from English. The SACS Instrument consists of 2 main assessments: lesion type (utilizing definitions and photographs) and lesion area by location around the ostomy. The study was performed in 2 stages: 1) the SACS language was changed and its content validity established; and 2) the instrument's content validity and inter-observer agreement (consistency) were determined among pairs of nurses who used the tool to assess peristomal skin lesions. Patients (included if they were >18 years old and receiving treatment/observation at 1 of the 4 participating stomatherapy units) and 8 stomatherapy nurses also completed appropriate sociodemographic questionnaires. Of the 393 patients screened during the 7-month study, 100 (average age 56.74 +/- 14.03 years, 55 men) participated; most (79) had a planned operation. A little more than half (59) of the patients had colorectal cancer and 28 had their stoma site marked preoperatively by a stomatherapy nurse. The most common peristomal skin lesion risk factors were having an ileostomy and unplanned surgery. The content validity index of the entire Turkish SACS instrument was 1, and the inter-observer agreement Kappa statistic was very good (K = 0.90, 95% CI 0.80-0.99). Individual SACS item K values ranged from K = 0.84 (95% CI 0.63-1) to K = 1 (95% CI 1). Most (62.5%) nurses found the terms and pictures used in the SACS classification adequate and suitable, and 50% believed the Turkish version of the SACS instrument was a valid and suitable assessment tool for use by Turkish stomatherapy nurses. Validity and reliability studies involving larger and more diverse patient and nurse samples are warranted.