To reproduce: this.radScheduler1.RightToLeft = System.Windows.Forms.RightToLeft.Yes; this.radScheduler1.Appointments.Add(new Appointment(DateTime.Now, TimeSpan.FromHours(2), "آقای حقیقت")); Please refer to the attached screenshot. Workaround: private void radScheduler1_AppointmentFormatting(object sender, SchedulerAppointmentEventArgs e) { e.AppointmentElement.UseHtml = false; }