Introduction: The Prophylactic Antibiotic Regimens in Tumor Surgery (PARITY) randomized controlled trial (RCT) was the first study to prospectively enroll and randomize orthopaedic oncology patients in multiple centers internationally. The objective of this study was to describe recruitment patterns, examine the differences in enrollment across different PARITY sites, and to identify variables associated with differing levels of recruitment.Methods: Data from this study was obtained from the PARITY trial Methods Center and records of correspondence between the Methods Center and recruiting sites. We performed descriptive statistics to report the recruitment patterns over time. We compared recruitment, time to set up, and time to enroll the first patient between North American and international sites, private and public health care models, and the presence or absence of research personnel. Two-tailed non-paired t-tests were performed to test average monthly recruitment rates between groups. Results: A total of 602 patients from 36 North American and 12 international sites were recruited from 2013 to 2019. Average monthly enrollment increased each year of the study. North American sites were able to start up significantly faster than international sites (19.5 vs. 27.0 months p=0.04). However, international sites had a significantly higher recruitment rate once active (0.2 participants/month vs. 0.59 participants/month, p=0.023). Sites with research personnel were able to reach ‘enrolment ready’ status significantly faster than sites without research personnel (19.3 vs. 30.3 months, p=0.032), but there was no difference in recruitment once active (0.28 participants/month vs. 0.2 participants/month). Publicly funded sites were to recruit significantly more patients compared to private institutions (0.4/month vs. 0.17/month, p=0.03).Conclusions: As a collaborative group, the PARITY investigators increased the pace of recruitment throughout the trial, likely by increasing the number of active sites. The longer time to start-up at international sites may be due to the complex governing regulations of pharmaceutical trials. Nevertheless, international sites should be considered essential as they recruited significantly more patients per month once active. The absence of research support personnel may lead to delays in time to start up. The results of the current study will provide guidance for choosing which sites to recruit for participation in future collaborative clinical trials in orthopaedic oncology and other surgical specialties.