SUMMARY—The influence of exogenous infusion of prostaglandins (PGs) of the F2αand E2series and of indomethacin on micturition cycles was investigated in 30 anaesthetised female dogs. In 30 other animals, urethrovesical disconnection was performed to study the action of PGs and of indomethacin without the muscle continuity factors.In the intact animal model during vesical distension, PGElproduced a significant urethral pressure drop and a dose‐dependent reduction in the threshold micturition volume. PGF2αproduced a significant urethral pressure rise. At doses higher than 0.3 μg/kg, PGF2αreduced the threshold micturition volume. On the other hand, indomethacin significantly increased the threshold micturition volume and reduced the maximum intravesical pressure.In the disconnected model, PGE2produced a dose‐dependent decrease in the resting urethral pressure and hardly affected the intravesical pressure; PGF2αproduced a dose‐dependent increase in both urethral and intravesical pressures.Thus it is suggested that endogenous PG release during vesical distension could play a facilitatory role in