The aim of this study was to compare the economic revenue related to the use of 
low- or high-efficacy anthelmintic drugs within suppressive or strategic schemes 
of treatment in growing heifers. Heifers raised in a semi-intensive grazing 
system in southern Brazil were used. Levamisole and ivermectin were selected as 
the high- and the low-efficacy drugs, respectively, based on a previous efficacy 
test. Subsequently, these drugs were used within strategic (Strat; four times 
per year) or suppressive (Supp; once a month) treatment regimens in the heifers, 
and their liveweight and eggs per gram of feces counts were monthly evaluated 
during a 13-month period. The total costs of the treatments and their 
cost-benefit ratio in regard to liveweight gain were calculated. Final mean 
liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 
(Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a 
high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 
14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. 
Total cost of the efficacy test (US$ 374.79) could be paid by the additional 
liveweight gain of 20 heifers from the Strat-High group. These results showed 
that it would be preferable not to treat the heifers against GIN if compared 
with treating them with a low-efficacy drug. In addition, we showed that the use 
of four treatments per year with a high-efficacy drug-selected by efficacy 
test-resulted in a profitable management to control GIN in growing heifers 
raised in a semi-intensive gazing system in southern Brazil.