The Auckland-based company made a loss of $500,000 in the six months ended December 31, from a profit of $4.2 million a year earlier, it said in a statement.
That was at the top end of its November forecast, on sales which rose eight percent to $108.5m.
Tourism Holdings cut its forecast annual profit, excluding costs from the merger with Kea and United, to between $3m and $4m from an expected $6.7m, and $4.3m in 2012.
Forecast earnings before interest and tax (EBIT) were lowered to a range of $14m to $16m from previous guidance of $19.3m.
"The strong and sustained rise of the Australian dollar against the currencies of core inbound tourism markets is entrenching perceptions that Australia is an expensive destination," chief executive Grant Webster said.
"We are taking steps to put in place a cost structure that reflects these weak demand conditions, but we expect the business to underperform our previous forecasts."
Last year's merger of its campervan rental business with two rivals was forecast to lift Tourism Holding's annual revenue to $241.3m in 2014 from this year's $200m, with profit rising to $14.8m from this year's $4.5m.
The board declared an interim dividend of two cents per share.
Tourism Holdings New Zealand rentals revenue fell 20 percent to $20.2m in the period from a year earlier, and posted an ebit loss of $2.2m from a profit of $2.9m in 2011.
Australian rental revenue increased one percent to $37.4m with EBIT unchanged at $3.4m, while US rental revenue rose one percent to $11.4m and EBIT gained five percent to $6.4m.
The tourism business, which includes the Waitomo Caves attraction, showed a three percent fall in sales to $8.9m, and ebit increased 14 percent to $800,000.