1 The pharmacological activity of phenylacetyl-Phe-Ser-Arg-N-(2,4-dinitrophenyl)-ethylenediamine (TKI), a tissue kallikrein speci®c inhibitor, was assessed using models of nociception and in¯ammation in mice. 2 Injection of TKI (13.6 ± 136 mmol kg 71 , i.p. or 41 ± 410 mmol kg 71 , s.c.) produced a dose-related inhibition of the acetic acid-induced writhes (by 37 to 85% or 34 to 80%, respectively). The antinociceptive activity of TKI (41 mmol kg 71 , i.p.) was maximal after 30 min injection and lasted for 120 min. The e ect was unaltered by pretreatment with naloxone (8.2 mmol kg 71 , s.c.) or bilateral adrenalectomy. 3 TKI (41 and 136 mmol kg 71 , i.p.) produced a dose-related decrease of the late phase of formalininduced nociception by 79 and 98%, respectively. At 136 mmol kg 71 , i.p., TKI also shortened the duration of paw licking in the early phase by 69%. TKI (41 and 136 mmol kg 71 , i.p.) also reduced the capsaicin-induced nociceptive response (by 51 to 79%). 4 TKI (41 mmol kg 71 , i.p. or 410 mmol kg 71 , s.c.) reduced the oedematogenic response, from the second to the ®fth hour after carrageenin injection by 36 to 30% or by 47 to 39%, respectively. 5 Pretreatment with TKI (41 mmol kg 71 , i.p.) reduced the capsaicin-induced neurogenic in¯ammation in the mouse ear by 54%. 6 It is concluded that TKI presents antinociceptive and antiin¯ammatory activities mediated by inhibition of kinin formation by tissue kallikrein in mice. The results also indicate that the tissue kallikrein-dependent pathway contributes to kinin generation in nociceptive and in¯ammatory processes in mice.