In 259 subjects at risk to have inherited autosomal dominant polycystic kidney disease (PKD), the frequency of symptoms consistent with urinary tract infection, haematuria, back and abdominal pain, hypertension, renal stones, and end-stage renal failure was evaluated. The diagnosis of PKD was made in 140 of these subjects (54 per cent). At the time of the study, 36 per cent of males and 7 per cent of females with PKD were asymptomatic, normotensive, and denied any previous problems. In patients younger than 30 years, 66 per cent of males but only 11 per cent of females were asymptomatic. In female patients, urinary tract infection (69 per cent) and hypertension (61 per cent) were the most frequent clinical manifestations. In contrast, in males with PKD, these problems were present in only 19 per cent and 42 per cent, respectively. Frequency of other clinical manifestations was similar in women and men with PKD. End-stage renal failure was present in 5 per cent of the 81 patients younger than age of 40, in 33 per cent of the 27 patients 40-49 years old, and in 47 per cent of the 32 patients aged 50 years or more. Physical examination was unreliable in estimating kidney size in most patients, particularly in early stages of the disease. Hypertension and symptoms such as haematuria and back pain, but not urinary tract infections, correlated well with renal size measured by radiograms.