Objective: The aim of this study was to compare uroflow parameters of patients with pure constipation against those with constipation plus lower urinary tract symptoms (LUTS) and a control group (no constipation). Materials and methods: During August 2012 to March 2014 three groups of patients were enrolled into the study: group C (constipation only), group CL (LUTS plus constipation) and group N (control: no constipation or LUTS). Dysfunctional elimination syndrome (DES) scores, uroflowmetry/electromyography (uroflow-EMG) findings, postvoiding residual urine (PVR) and rectal diameter were measured and compared between groups. Results: Groups C, CL and N comprised 80, 100 and 30 patients, respectively. Average DES scores were 12.6, 18.7 and 4.9, respectively. Voided volume (as a percentage of expected bladder capacity) was 104%, 89% and 101%; and average maximum flow rate was 21.1 ml/s, 36.4 ml/s and 28.1 ml/s, respectively. Pelvic floor muscle activity during voiding was seen in 40.0%, 42.0% and 6.7% of patients in groups C, CL and N, respectively; and pathological PVR was seen in 26.3%, 55.0% and 3.3% of patients in the respective groups. Average rectal diameter was measured as 38.6 mm, 36.4 mm and 28.1 mm in groups C, CL and N, respectively. Conclusion:: This study found that abnormal voiding parameters are present in patients with constipation even if LUTS are not present. Therefore, it is important that all patients presenting with constipation have their voiding function evaluated.