Fifteen patients with the loin pain and haematuria syndrome (LPH) were compared with 10 patients with complicated renal stone disease referred to the same tertiary centre and matched for age, sex and duration of illness. LPH patients had a history of three times more medically unexplained somatic symptoms other than loin pain (p < 0.01) and a higher proportion took analgesics regularly (p < 0.01). The onset of pain was associated with an adverse psychologically important life-event in eight of the LPH patients but in none of the controls (p < 0.02). LPH patients more frequently recalled serious parental illness and disability in childhood (p < 0.001) than controls, and a higher proportion felt responsible for causing or alleviating parental illness or distress (p < 0.05). LPH subjects scored higher in the 'paternal care' dimension of the Parental Bonding Instrument (p < 0.05). No difference was found between LPH patients and controls in terms of current depression and anxiety but both groups exhibited high rates of lifetime depression. LPH patients expressed lower levels of anger and hostility (p < 0.002) than did controls. Our observations suggest that psychological factors are of major importance in the aetiology of LPH, which may represent a type of somatoform pain disorder.