Literature on fluid therapy for surgery is updated in regard to coagulation, blood loss and post-operative complications. Haemorrhage depends on the surgical intervention but also on the chosen fluid therapy with artificial colloids affecting coagulation competence and in turn the blood loss. Furthermore, a stable central blood volume as indicated by plasma pro-atrial natriuretic peptide requires a calculated fluid surplus by approximately 2.5 l. Randomized controlled trials recommend haemorrhage to be treated by administration of a crystalloid; however, if the calculated excess of fluid approaches 2 l, albumin may be added.