Background: Malaria is a public health concern in Africa. At the socio-economic level, it represents a brake on the national growth through an increase of health spending, drop of productivity and high rate of absenteeism at the workplace. Some companies have implemented malaria control measures to improve their performance, but the vast majority are slow to follow this approach. Using the cost-of-illness approach, the objective of this study was to estimate the economic impact of malaria in two companies with 24-hour daily activity based in Douala, Cameroon: an agro-food industry nicknamed "AGRO" and a security company nicknamed "SECU".Method: A retrospective analysis of medical and financial records of these companies was carried out to calculate the economic cost of absenteeism, prophylaxis, Internal Management of Malaria cases (IMM) and External Management of Malaria cases (EMM) to these companies. A malaria screening campaign was carried out also in each company in one day from 8 a.m. to 4 p.m. The clinical, anthropometric and socio-demographic data of the employees were collected before the collection of a drop of blood which was subsequently analyzed under the Cyscope fluorescence microscope (Partec-Sysmex, Münster, RFA). Results: Analysis of retrospective data revealed that the prevalence of symptomatic malaria cases had decreased by 8.9% and 25.1% respectively at AGRO and SECU between 2010 and 2012. Regarding the prospective component, 372 employees of the two companies were included in the study. The prevalence of malaria was 26.83% and 26.44% respectively at AGRO in January 2013 and SECU in February 2013. Malaria-related absenteeism accounted for 5% and 17% of general absenteeism at AGRO and SECU respectively. The cost of an EMM accounted for 19.5% and 40.5% of the monthly income of AGRO and SECU workers respectively. Each year, malaria generates a shortfall of US$ 26,426 and US$ 136,824 respectively to AGRO and SECU. Conclusion: Malaria have a negative impact on companies. However, early detection of suspected cases, campaigns to distribute insecticide-treated mosquito nets, Information, Education and Communication within the company could reduce this impact.