Two hundred and fifty-three men (age 69.2 +/- 7 years) undergoing prostatectomy for bladder outflow obstruction were studied. The aims were to determine the distribution of voiding pressures and their relationship to presenting symptoms and urodynamic findings. Symptoms were scored by means of a standardised questionnaire and urodynamic studies were performed. Within this study group, high obstructive symptom scores were associated with low flow rates and high urethral resistance. However, high voiding pressures were not associated statistically with low flow rates or obstructive symptoms. Voiding pressures followed a unimodal, parametric distribution and a significant number of men had voiding pressures within the normal range: 9.1% had voiding pressures less than 55 cm H2O and 27.7% less than 75 cm H2O. Irritative symptoms, on the other hand, correlated significantly with obstructive symptoms, high voiding pressures and urethral resistance. Furthermore, high voiding pressures were associated with small cystometric bladder capacities, low compliance and detrusor instability. Whilst these clinical and urodynamic parameters were associated statistically with voiding pressures, none proved specific in being able to identify men with voiding pressures in the high or low end of the range.