INTRODUCTION
Much of the research undertaken in Thailand concerns itself with the treatment
population and the convicted population (Perngparn et al 1992), both are visible groups in an
otherwise invisible population. As Lee pointed out, research into illicit behaviour is
notoriously difficult (Lee 1993), hence a predominance of studies on these population groups.
The research is especially concerned with opiate users as treatment centres and prisons have
historically dealt with a larger number of opiate users than any other type of user
(Poshyachinda 1981). There are however some exceptions where researchers have tried with
some success to establish a more accurate picture of overall drug use in Thailand.