Urinary tract infection is one of the most frequently seen 'medical' complications in pregnancy. The pioneering work of Edward Kass discovered that 6% of pregnant women had asymptomatic bacteriuria associated with increased prematurity and perinatal mortality compared to women with sterile urine. Screening for bacteriuria in pregnancy has become routine. The prevalence of asymptomatic bacteriuria as well as the associated complications described by Kass in 1962 are higher compared to most data collected in the 1980s and late 1990s in different populations in various parts of the world. Other factors such as vaginal colonization have been recognized as important contributors to preterm labour. The value of screening for bacteriuria has to be re-addressed considering methods, significance and costs. Treatment of urinary tract infection in pregnancy is critically reviewed.