Abdominocentesis was performed, left of the midline and medially and cranially to the foramen of the left subcutaneous abdominal vein, on 60 cows, subdivided into three groups, to assess the best technique; a different technique was used for each group. In the first, a Gratzl puncture was used. In the second, a Gratzl puncture, modified by the addition of eight holes was used, and in the third a modified Gratzl puncture cannula, through which a sterile fenestrated plastic tube was introduced into the abdominal cavity. The successful recovery of peritoneal fluid found to be dependent on the puncture technique and the prevailing disease. All three techniques were equally suitable for animals with a generalised peritonitis. The modified Gratzl puncture cannula, with or without the insertion of the fenestrated plastic tube, can be recommended in cases of traumatic reticulo-peritonitis or in animals with equivocal responses to tests of abdominal pain.