Introduction. Culicoides pachymerus is a major pest species for the inhabitants of the western Boyacáprovince of Colombia.Objective. The effect of a repellent lotion based on p-menthane-3,8-diol (16%) and lemongrass oil(2%) was evaluated against the bites of C. pachymerus.Materials and methods. The repellent lotion was compared simultaneously with a control (notreatment) by human landing catches of C. pachymerus on the forearms of paired volunteers situatednear human dwellings. Protection percentage and protection time for 3 to 6 h after repellent applicationwas calculated. The test was repeated ten times.Results. Only two females of C. pachymerus were collected on arms with the repellent treatment. Incontrast, the mean biting rate in the untreated control was 47.7 midges/person/10 min. Mean protectionpercentage of the repellent was 100% up to 4 h and 99.5% up to 5 h. Protection time was 332.2 and338.2 min in the two replicates where bites of C. pachymerus were confirmed. In the remaining eightreplicates protection time exceeded the test duration.Conclusion. The repellent showed high efficacy against C. pachymerus, up to 5 h post-application.doi: http://dx.doi.org/10.7705/biomedica.v32i3.738