Pre-analytical errors still represent nearly 70% of all errors occurring in the laboratory, constituting a danger, a waste of time and an additional cost to the patient. The control of the different components of the pre-analytical step is important for the validity of the hemostasis exploration tests. The purpose of our work is to identify the main anomalies of the pre-analytical phase in hemostasis and to propose the means to correct them. We conducted a prospective and descriptive study on the pre-analytical phase of hemostasis. It was in the form of a survey, identifying the main errors related to this phase. It was performed at the Hematology laboratory of the Avicenna Military Hospital of Marrakech and spread over a period of 4 weeks. Our investigation took place at the hemostasis room, which received the collection tubes from the various hospital departments and the blood drawing room (for non-hospitalized patients). The hemostasis room received 400 prescription cards and their corresponding tubes. The parameters related to the prescription file: full name and gender of the patients, were mentioned on all the cards received and they were in conformity with those marked on the corresponding tube. The age of the patients and their clinical and therapeutic informations were mentioned in 73% and 13% of the exam requests, respectively. For the pre-analytical hemostasis parameters related to the blood collection: 63% of samples were taken at the laboratory's blood drawing room, while 37% came from the various hospital departments. Time of the realization of the samples was not mentioned on the cards or on the labels of the tubes. The anticoagulant used for all samples was sodium citrate at a concentration of 3.8%. The filling of the tubes was noncompliant in 22.25%. Registration and triage of the tubes systems were manual. Centrifugation was carried out at a rotation speed of 5000 G for 5 minutes and at a temperature set at 22°C. Hemolyzed samples accounted for 3% of the tubes.