Background: Traditionally some people employ Ocimum basilicum (Shaspram) to relieve the symptoms of dyspepsia. We therefore studied the effects of oral extract of this medicinal plant on functional dyspepsia. Methods: In a double-blind placebo-controlled clinical trial, the effect of a four-week treatment of Shaspram was evaluated on functional dyspepsia. Two hundred cases from all patients referred for dyspepsia without having any obvious pathologic signs were randomly divided into case and control groups (100 each). The hydroalcoholic extract of leaves of Shaspram was prepared and used. Patients were asked to have 30 drops of prescribed medications (placebo or the extract, equal to 1.5 gram leaves powder) daily at 30 min before lunch and dinner for four-weeks. Severity was scored for each symptom on a numbered scale and the results compared with the results of placebo group or pretreatment period. Results:Patients in drug group responded to treatment better than patients in placebo group (P<0.001). Shaspram was more effective in female and young patients. Patients with functional dyspepsia that had dysmotility problems also responded to Shaspram better than others. Conclusion: Ocimum basilicum seems to relieve the symptoms of functional dyspepsia especially in female and young patients with dysmotility.