The Parasitology-Mycology Laboratory's analytical process involves three stages: pre-analytical, analytical, and post-analytical. Our focus is on the pre-analytical phase (PAP). This study addresses managing PAP non-conformities at Mohammed VI University Hospital in Oujda, aligning with quality standards like ISO 15189 and GBEAand aiming to detect and resolve deviations. This 84-month retrospective study analyzed specimens at the Parasitology-Mycology lab in the Mohammed VI University Hospital in Oujda. Examination requests were made through the hospital's IT system (HOSIX), and samples were transported pneumatically. After administrative and technical checks, samples were rejected, processed, or retained for correction based on findings. Reports of non-conformities were sent to prescribers via the IT system. Data were analyzed and flowcharts were created using Microsoft Excel (Redmond, USA). During the study period, prescription errors were the most common non-conformities (65.88%; n=56), followed by sample nature errors (29.41%; n=25) and sample packaging errors (4.70%; n=4). Prescription discrepancies, mycological exams for patients on antifungal treatment or carrying Henna, and missing clinical information were the main causes. Outpatient samples accounted for 29.41% of non-conformities, while inpatient samples accounted for 70.59%. The majority of inpatient non-conformities came from the dermatology department (n=42; 49.41%). The pre-analytical phase in Parasitology-Mycology is crucial for ensuring accurate results, involving the coordination of various stages such as staff training, documentation, and non-conformity management. Prescription errors were predominant among non-conformities, followed by sample nature and packaging errors. Outpatient samples had fewer non-conformities compared to inpatient ones, possibly due to supervision by a biologist. Non-conformities lead to therapeutic, prognostic, and economic issues, underscoring the need for their reduction. Corrective actions are crucial, along with establishing policies for error detection and control. Potential causes of non-conformities can be analyzed using methods like the 5M approach. Suggestions for improvement include distributing a validated sampling manual, creating electronic test request forms, staff training, ongoing training programs, and regular meetings for information exchange. The pre-analytical phase in Parasitology-Mycology is crucial, demanding a quality-focused approach for strict adherence to procedures and traceability. Mastery of this phase ensures result reliability.