The pharmacodynamics and -kinetics of pipecuronium were studied in 12 patients, six of whom received 100 micrograms kg-1 for laryngectomy (Group L), and six who underwent choledochotomy after insertion of the T-drain and were given 50 micrograms kg-1 (Group C). Onset time and clinical duration were 2.3 and 109 min and 2.8 and 39 min in Groups L and C, respectively. All patients could be sufficiently reversed with neostigmine. Terminal half-lives were 101.5 min (Group L) and 179 min (Group C) in a three-exponent decay; the distribution volumes at steady state 0.339 l kg-1 (Group L) and 0.506 l kg-1 (Group C); the plasma clearance 3.4 ml kg-1 min-1 (Group L) and 2.5 ml kg-1 min-1 (Group C). Within 24 h, 38.6% and 37% were excreted unchanged in the urine and 4.4% and 1% as 3-desacetyl pipecuronium in Groups L and C, respectively. Within 24 h only 2% was excreted into the bile in Group C. Distribution volume and terminal half-life in Group C were positively correlated with pre-operative serum aminotransferase levels (P less than 0.005).