Peritonitis accounts for considerable morbidity and hospitalization in peritoneal dialysis (PD) patients. We investigated the factors related with time of hospital stay, especially focusing on the peritoneal cell profiles at the time of hospital admission in PD-related peritonitis. Eighty peritonitis attacks were evaluated. Data were collected at the time of hospital admission, clinical and biochemical parameters, including initial systemic and dialysate white cell counts (including percentage and differential count of neutrophils and lymphocytes) and length of hospital stay. Peritoneal leukocyte (r = +0.289, p = 0.009) and neutrophil counts (r = +0.403, p < 0.0001), peritoneal neutrophil percentage (r = +0.492, p < 0.0001), time of hospital admission (r = +0.498, p < 0.0001), and C-reactive protein (CRP) (r = +0.231, p = 0.042) were positively correlated; lymphomononuclear cell percentage (r = -0.650, p < 0.0001) was negatively correlated with hospitalization length. Hospital admission >= 24 hours of symptom onset was associated with higher CRP, dialysate leukocyte and neutrophil counts, longer hospitalization, and with lower dialysate lymphomononuclear cell percentage compared to admission < 24 hours (p = 0.04, p = 0.04, p = 0.005, p < 0.0001, and p = 0.04, respectively). In multiple linear regression, the time of hospital admission (p = 0.002), initial peritoneal neutrophil count (p = 0.011), and lymphomononuclear cell percentage (p < 0.0001) were independently associated with hospitalization length. Hospital admission within first 24 hours of peritonitis symptoms onset is of vital importance; delayed admission is associated with higher peritoneal leukocyte and neutrophil counts, and increased length of hospital stay.