One hundred and twenty‐five Dutch servicemen returning from central Africa after a short deployment were enrolled in a study aimed at assessing the effectiveness of malaria prevention measures. None of the persons developed an episode of clinically overt malaria during or after deployment, and no antibodies against blood stages of Plasmodium falciparum could be found. However, antibodies against the circumsporozoite protein (CS) of P. falciparum were demonstrable in 14 persons (11.2% of the study population) by an ELISA test using the recombinant CS‐antigen R32tet 32, while one person only was positive in an IFA test based on schizonts of P. fieldi as antigen. We concluded that the anti‐CS‐positive servicemen were probably bitten by mosquitoes carrying P. falciparum parasites while the IFA‐positive person was possibly infected by P. vivax , P. ovale or P. malariae parasites. There was no significant association between the different antimalaria preventive measures and the development of anti‐CS antibodies. Therefore mefloquine prophylaxis as the single most widely used preventive measure in this group of servicemen was possibly a major contributing factor in averting development of overt malaria.