Aim: This study was conducted to determine the effect of hot water application by immersion method to the legs of pregnant women with Restless leg syndrome (RLS) on their complaints about RLS. Methods: The study is a pretest-posttest randomised controlled. The study was performed with pregnant 29 women. The data were collected using Personal Information Form, International RLS Study Group Diagnostic Criteria, and the International RLS Rating Scale (IRLS). Hot water application was made of intervention group (IG). No application was made in the control group (CG) other than routine care and follow-up. The application was made for 20 minutes before bedtime for seven days. No application was made in the CG other than routine care and follow-up. Results: Descriptive and gestational characteristics of the pregnant women in both groups were similar (p>0.05). In pretest measurements, IRLS total score of the IG was 26.38±6.82, the score of the CG was 22.06±5.56 and the groups were similar to each other (p>0.05). While posttest total score was 8.23±6.84 in the IG and 21.18±6.32 in the CG and the difference between the groups was statistically significant (p<0.001). Discussions: Hot water application made to the legs of the pregnant women with RLS decreased the severity of RLS. Clinical trials name and ID: The Effect of Hot and Cold Water Application on Pregnant Women with Restless Leg Syndrome (RLS); NCT04786314