Côte d'Ivoire produces cucumber (Cucumis sativus L.) in peri-urban areas. The cultivation is threatened by a disease which symptoms are similar to a virus disease despite the use of varieties so-called resistant to virus diseases. In order to implement a control method, a comprehensive diagnosis was made. After assessing the extent of the disease in two large cucumber production areas on the outskirts of the city of Abidjan, two direct and indirect diagnoses were made. The first one was made on the basis of observation and description of the characteristic symptoms of viral infection. As for the second one, samples of symptomatic and asymptomatic leaves were randomly collected from infected plots. Molecular analyses were done using PCR followed by reading on an electrophoresis gel. 92.42% of cucumber plants were infected in the plots with a high average severity of 4. The direct diagnosis led to conclude that the cucumber was CMV-infected. PCR products showed the presence of CMV virus responsible for cucumber mosaic in infected leaves. The symptoms developed by cucumber plants and the identification of the viral agent associated with the symptoms justified an infection of cucumber plots in peri-urban areas of Abidjan by CMV with a much stronger pressure than 31 years earlier.