Fecal samples from 38 individually recognized vervet monkeys (Chlorocebus aethiops) from Loskop Dam Nature Reserve, South Africa, were examined for helminths. Analysis of 272 fecal samples revealed that all individuals were infected. Eggs of 5 helminth species were recovered. Prevalence of infection for Trichuris sp. was 92%, Oesophagostomum sp. was 84%, an indeterminate hookworm was 71%, an indeterminate spirurid was 68%, and Strongyloides sp. was 24%. Social group membership, age, and sex were not predictors of infection with any of the parasites detected. Monthly prevalence of parasites was not significantly correlated with mean monthly precipitation, minimum temperature, or maximum temperature, although some variables were correlated. Monthly prevalence of Oesophagostomum sp. was positively correlated with mean monthly minimum temperature (r  =  0.7152, n  =  12, P  =  0.013), mean monthly maximum temperature (r  =  0.6012, n  =  12, P  =  0.050), and mean monthly precipitation (r  =  0.6216, n  =  12, P  =  0.041). Monthly prevalence of Strongyloides sp. was positively correlated with mean monthly precipitation (r  =  0.7005, n  =  12, P  =  0.016). These are the first data on the parasitic infections of wild C. aethiops in Mpumalanga province of South Africa.