Abstract Background and Aims Patients with end-stage renal disease (ESRD) frequently need to change dialysis modality. While the transition from peritoneal dialysis (PD) to hemodialysis (HD) is not an uncommon occurrence, the opposite is less frequent and much less studied. The aim of this study was to compare the outcomes of patients who started renal replacement therapy (RRT) with PD and patients who transitioned from HD to PD. Method Retrospective single-center cohort study with patients who started PD between 1st January 2010 and 31st December 2017, with a median follow-up of 60 months. Patients were separated in two groups, one where the initial RRT was PD (“PD first”) and another who transitioned from HD to PD (“Previous HD”). Clinical outcomes (complications during PD, technique failure, hospitalizations) and dialysis adequacy were compared between the two groups. Results Among the 137 patients included in this study, 22 transitioned directly from HD and 115 were PD first. The population included 63,7% of male gender, with a mean age of 52,9 ± 14,6 years and a mean Charleston score of 4,4 ± 2,2. Sixty percent had diabetes and 65,2% had hypertension. Median time on PD was 112,7 months (IQR 44,2). Patients who transitioned from HD had lower residual diuresis both at start of PD (1153 ± 920 vs. 1880 ± 924; p < 0,007) and at the end of follow-up (750 ± 1074 vs. 1252 ± 836; p < 0,037). A higher rate of UF failure was observed in patients who transitioned from HD (30,1% vs. 10,9%; p = 0,036). Annual rate of peritonitis and hospitalization was the same between groups. Technique failure (death or hemodialysis transfer) was not different between groups (52,1% vs. 53,6%, p = 0,903; logrank 0,301). Conclusion Residual diuresis was lower in the group that was previously in HD, which might be explained by the negative impact of HD in the preservation of renal residual function. Despite comparable DM prevalence and similar rates of PD-related infections a greater proportion of previous HD patients developed UF failure. Previous HD can predict a more complex volemic control in PD because of a lower residual renal function. Despite that, technique failure, hospitalizations, infections and outcomes at end of follow-up were similar in both groups. PD can be considered a viable dialysis technique in terms of outcomes in patients transferred from HD. Table 1:Analysis of HD first versus PD first groups.VariableTotal (n = 135)Previous HD (n = 22)PD first (n = 113)P-valueGender (male), n (%)86 (63.7)14 (60.9)72 (64.3)0.756Age at start of PD (years) (a)52.9 ± 14.652.0 ± 15.553.0 ± 14.60.772Time in PD (months) (a)112.7 ± 44.297.7 ± 56.2115.2 ± 41.60.107Hypertension, n (%)88 (65.2)11 (47.8)77 (68.8)0.055Diabetes, n (%)54 (60)10 (43.5)44 (39.3)0.709Charleston Score (a)4.4 ± 2.24.6 ± 2.34.3 ± 2.20.519PD adequacyKtV at PD start (a)2.7 ± 0.82.5 ± 0.72.7 ± 0.90.201KtV at end of follow-up (a)2.1 ± 0.61.9 ± 0.72.1 ± 0.60.250Residual diuresis at PD start (mL/24h) (a)1769 ± 9551153 ± 9201880 ± 9240.007Residual diuresis at end of follow-up (mL/24h) (a)1175 ± 889750 ± 10741252 ± 8360.037UF failure, n (%)17 (14)6 (30.1)11 (10.9)0.036ComplicationsAnnual peritonitis rate (a)0.1 ± 0.20.1 ± 0.30.1 ± 0.20.855Annual exit tunnel infections rate (a)0.0 ± 0.10.0 ± 0.10.0 ± 0.10.845Annual tunnel infections rate (a)0.0 ± 0.00.0 ± 0.00.0 ± 0.00.890Annual hospitalizations rate (a)0.2 ± 0.50.2 ± 0.50.2 ± 0.50.955Outcomes at end of follow-up, n (%)0.071 PD maintenance31 (23)4 (17.4)27 (24.1) HD transfer52 (38.5)5 (21.7)47 (42) Kidney transplantation29 (21.5)7 (30.4)22 (19.6) Death20 (14.8)7 (30.4)13 (11.6) Loss of follow-up3 (2.2)0 (0)3 (2.7)