Unilateral inguinal hernia in a young child poses a management dilemma. Most paediatric surgeons prefer to explore the contralateral side routinely based on the reports showing a high (50%–100%) incidence of patent processus vaginalis (PPV) in young infants, while autopsy studies have shown that in 20%–30% of the population the PPV remains patent. We reviewed all the patients who underwent bilateral explorations for clinically apparent unilateral inguinal hernia and studied the pattern of positive explorations according to patient's age at the time of operation. We also retrospectively reviewed all patients who underwent unilateral inguinal herniotomy during the same period to see the incidence of development of contralateral inguinal hernias. Between January 1973 and December 1985 there were 941 patients with unilateral inguinal hernia under 2 years of age; 390 underwent contralateral explorations while 551 underwent unilateral inguinal herniotomy only. A PPV was present in 191 (49%) patients on contralateral exploration with the incidence of 100%, 66%, 52%, 51%, 52%, 43%, 39%, 30%, and 25% in children below 1 week, 1 week to 1 month, 1 to 2 months, 2 to 3 months, 3 to 4 months, 4 to 5 months, 5 to 6 months, 6 to 12 months, and 12 to 24 months, respectively. Of the 551 patients who underwent unilateral inguinal herniotomy, 54 subsequently developed a hernia on the contralateral side. It appears that the process of obliteration of the PPV continues in the first few months of life and only about 10% of patients with a unilateral inguinal hernia go on to develop a contralateral hernia clinically. Therefore, the presence of a PPV at exploration does not necessarily mean possible development of a hernia at a later stage and hence need not be considered a reason for routine exploration of the contralateral inguinal region.