However, the index remained in negative territory at a seasonally adjusted score of 48, compared to July's reading of 38.
July's lower level was partly a result of disruptions from strikes.
"The swifter resolution of labour disputes in August 2011 contributed to the 'normalisation' of the trade environment," Sacci said in a statement.
The Tai had been in negative territory since April 2011 and was 7 points below the last positive reading in March 2011.
The Tai is a composite index of sales volumes, new orders, supplier deliveries, inventory levels and employment. A reading of 50 reflects no change and above 50 indicates a positive level. Below 50 is negative.
Sacci said all components of trade activity performed better than in July 2011.
However, the 2011 strike season had a negative impact on employment conditions, with the index on employment in the trade environment dipping to 42 in July and only partially recovering to 45 in August 2011.
The employment prospects index - which looks at conditions in six months' time - was in negative territory at 49.
"Given the uncertain businesses and economic climate, the trade sector finds it difficult to accommodate above-inflation wage settlements while maintaining the current size of the workforce," Sacci said.
"The potential implications for employment in the broader economy remain concerning."
The Trade Expectations Index recovered in August by 5 points to 57, although this was still 8 points below the February 2011 level.
"The trend towards negative territory seems to have abated," Sacci said.
The outlook for all elements of the trade expectations survey improved. However, rising costs including fuel and utilities would probably continue to put trade margins under pressure.
"Although marginally improved from July to August, Sacci remains concerned about the weak performance in the trade environment and the implications of such performance for the broader economy and for the 2012 outlook."