Several indolyl isoquinoline derivatives were synthesized and evaluated for their antiinflammatory and antiproteolytic activities. These derivatives possessed 9.2-32.4% inhibition at a dose of 100 mg/kg i.p. against carrageenin-induced oedema. Four of these derivatives (IVb, IVd, IVe and IVk) exhibited high potency in inhibiting oedema. The degree of inhibition of trypsin-induced hydrolysis of bovine serum albumin, in vitro, by compounds IVb, IVd, IVe, IVi, IVj, IVk and IVl ranged from 10-42% at a final concentration of 1 mmol/l. In addition, these agents exhibited relatively non-toxic nature and their approx. LD50 was greater than 1000 mg/kg i.p.