Accidental poisoning of young children by household products and medicines remains a serious problem in many countries. Child resistant packaging, i.e. packages of which the opening and closing mechanisme requires manipulation and/or forces beyond the limits of children's exertions, has been developed to counter this problem. It is important to standardise field trials of such packaging to ensure adequate protection for the population at risk (the inquisitive and ingenious youngsters), while permitting access by adults. Testing variables which were studied were the age boundaries of the child panel and of the adult panel. Tests were conducted on four types of child resistant reclosable containers; two of the push-and-turn type, two of the squeeze-and-turn type. Inclusion of children between 24 and 41 months old in the test panel did not significantly affect the proportion of subjects who were able to gain access to the containers. However, the inclusion of adults, in the age-range 60-75 yr, in the test was found to provide the best safeguard against overcomplex and difficult packaging coming on to the market. Any standard&d tests need to take into account the finding that in a testing situation most of the children between 42 and 51 months do not use their teeth. In normal situations nevertheless, children of one-two years old, the age group in which most of the poisoning accidents happen, frequently resort to using their teeth when they are unable to open containers by hand.