1 A total of three hundred and nineteen new chemical entities (NCEs) were investigated in man for the first time between 1964 and 1985 by seven UK-owned pharmaceutical companies. The majority (96.2%), were self-originated by the UK company or one of its overseas subsidiaries. 2 There was an increase in the number of NCEs investigated each year in man, doubling from an average of 12 per year up to 1980, to over 20 per year between 1981 and 1985. The majority of first drug evaluations in human volunteers were carried out in the UK (92.2%), in contrast to evaluation of new medicines in patients, where 42.9% were first tested outside the UK. 3 The majority of NCEs evaluated in man (78%), were in four therapeutic classes: anti-infectives (32%), anti-allergics (22%), drugs acting on the central nervous system (13%) and cardiovascular system agents (11%). 4 By the end of 1985, 49 (15.4%) of these NCEs had been marketed in the UK and 198 (62.0%) discontinued from further development. The main reasons for termination were inappropriate pharmacokinetics in man (39.4%), and lack of clinical efficacy (29.3%). 5 Average development times increased from less than 2 years between 1964 and 1965, to around 8 years in the 1980s with a consequent reduction in the effective patent life.