The present study is aimed to investigate the effect of red sugar on functional constipation in children compared to figs syrup.Treatment of constipation in childhood improves gastrointestinal function in the future and regular bowel habit. Red sugar is an effective ingredient in the treatment of constipation. Figs syrup is the other common natural substance used to treat constipation in children. Conducted studies on these two substances and similar herbal substances have shown their beneficial effects, but in a conducted study, it is reported that the effect of fig syrup is less than the chemical material.This Randomized Controlled Trial (RCT) Study was done in 2016. First, by performing an examination and filling out the identifying form of the patient's health status, mothers respond to the designed questionnaire. 30 children with constipation were treated with the usual drug, fig syrup, and 30 other children received red sugar. After a 4-week treatment period, the examination was conducted again and the questionnaire was filled out again. The changes following the intervention were measured and the status before and after treatment were compared as well. The analyses were performed using SPSS 20 (SPSS for Windows, SPSS Inc., Chicago, IL, USA).In this study, there was no significant difference between effects of red sugar and fig syrup in terms of the frequency of fecal excretion, and pain at the time of excretion (p = 0.264). However, the fig syrup was more effective in reducing the anorexia (p < 0.001) and abdominal pain compared with fig syrup (p < 0.001). Also fig syrup was more effective in inducing diarrhea (p = 0.019).In general, treatment by red sugar has been effective in improving the functional characteristics of constipation in children; and did not show any complication and toxic effects. It is easily accessible at affordable prices to resolve childhood constipation.