Usually in in vitro fertilization (IVF) treatment; controlled ovarian hyperstimulation is started on the 2-3rd day of menstruation. However, in patient groups with limited time, waiting for menstruation for ovarian hyperstimulation has now been replaced by 'random start protocols'. In this case report, the ovarian stimulation responses of the same patient in the early and late follicular phases in different menstrual cycles were compared.