Abstract Background and Aims To study the incidence and intensity of cramps in patients with end-stage CKD during dialysis. Method In a cross-sectional study in 2021, 160 male and female patients on program dialysis (PD), aged 22 to 77 (53.3±7.11) receiving for 7.7 ± 1.83 (1 to 25) lasting 12 ± 0.24 hours per week (average KT / V 1.4 ± 0.03) on Fresenius and B. Braun devices. The intensity of cramps was assessed according to a numeric rating scale (NRS) from 0 to 10, as well as its impact on quality of life. To identify patients with intradialytic hypotension (IDH), we used the KDOQI guidelines, which define IDH as a 20 mm Hg decrease in systolic blood pressure (BP) from the origin, assessed over 3 consecutive sessions. All patients' blood serum was checked for phosphorus (P), calcium (Ca), parathyroid hormone (PTH). Results Patients were divided into 2 groups, presence 81 (51.0%) or absence 79 (49.0%) of cramps (Table 1). Among patients with diabetes, the frequency of absence of cramps is 2 times higher than among patients with diabetes (6% vs. 94%, respectively) (Table 2). Among patients with hypotension, only in 15% there were no cramps, while without hypotension 85% (Table 3). No statistically significant difference was found between the groups for any of the 3 parameters (PTH, P, Ca). Conclusion Painful muscle spasms have been insufficiently studied, although their impact on the quality life of dialysis patients is clinically significant. The first steps should be on correcting for potentially modifying risk factors, development of hypotension during a procedure and correction of phosphorus levels.