Background: Prolonged hospital stay before surgery is a risk for colonization with antibiotic-resistant microorganisms and possible antibiotic-resistant surgical site infections (SSI), which lacks acknowledgement in international guidelines for perioperative antibiotic prophylaxis. Method: Retrospective cohort study focusing on prophylaxis-resistant SSI in adult orthopedic implant patients; with emphasis on length of hospital stay prior to the index surgery. Results: We enrolled 611 cases of SSI (median age, 65 years; 241 females and 161 immune-suppressed) in four large implant groups: arthroplasties (n = 309), plates (n = 127), spondylodeses (n = 31), and nails (n = 46). The causative pathogen was resistant to the perioperative antibiotic prophylaxis regimen in 307 cases (307/611; 50%), but the length of pre-surgical hospitalization did not influence the incidences of prophylaxis-resistant SSIs. These incidences were (107/211;51%) for the admission day, (170/345;49%) within 10 days of delay, (19/35;54%) between 10 and 20 days, and (11/20; 55%) beyond 20 days of hospital stay before surgery. The corresponding incidences of methicillin-resistant staphylococci were 13%, 14%, 17%, and 5%, respectively. In adjusted group comparisons, the length of prior hospital stay was equally unrelated to future prophylaxis-resistant SSI (odds ratio 1.0, 95% confidence interval 0.99-1.01). Conclusions: In our retrospective cohort of orthopedic implant SSI, the length of pre-surgical hospital stay was unrelated to the incidence of prophylaxis-resistant pathogens.