Background & objectives: Pertussis is a bacterial respiratory infection caused by the Bordetella pertussis and Bordetella parapertussis. B. pertussis-specific antibodies can be detected by enzyme-linked immunosorbent assays (ELISAs). The antigens most frequently used as pertussis toxin (PT). The objective of this study is to determine whooping cough by enzyme immunoassay ELISA IgM. Methods: Antibodies IgM response to pertussis toxin was measured by enzyme-linked immunosorbent assay in 16 cases. Cases suspected with clinical symptoms typical of whooping cough and family contacts of children with pertussis were referred to The Laboratory of epidemic diseases in the National Institute of Hygiene, Morocco. Results: Out of 16 suspected cases, 4 (25%) were positive, 8 (50%) were negatives and 4 (25%) were doubtful. Interpretation & conclusions: The serology is particularly valuable for the diagnosis of pertussis is sensitive and specific and its sensitivity is not amended by the antibiotic, contrary to the culture and PCR, and is useful for the diagnosis in the case of investigations around a case of whooping cough or the date of the declaration of the disease is late to carry out the PCR technique. Our study carried out between 2013 and 2017 allowed us to note that the main contaminant is the members of the family.