Balancing the numerous benefits that may accrue from pesticide use on cotton, farmers face health hazards. Pesticide-induced acute symptoms significantly increased the cost of illness in a survey of 280 smallholder cotton growers in two districts of Zimbabwe. Cotton growers lost a mean of Z$180 in Sanyati and Z$316 per year in Chipinge on pesticide-related direct and indirect acute health effects. These values are equivalent to 45% and 83% of annual household pesticide expenditures in the two districts. The time spent recuperating from illnesses attributed to pesticides averaged 2 days in Sanyati and 4 days in Chipinge during the 1998/99 growing season. These pesticide health cost estimates represent lower bounds only; they omit chronic pesticide health effects as well as suffering and other non-monetary costs. Acute pesticide symptoms were determined in large part by pesticide use practices, notably the lack of protective clothing. Yet many smallholder farmers misunderstood pesticide health hazards, and so did little to protect themselves. Despite the use of simple color codes, 22% of smallholder cotton growers in Sanyati and 58% in Chipinge did not know how to order the four colored pesticide label triangles by toxicity. Better farmer education in exposure averting strategies is needed. Likewise, fuller accounting for hidden health costs in future would allow farmers to make more informed decisions about agricultural pest management.