Second quarter revenue at online fashion retailer ASOS was an impressive 49% ahead of the same period last year, but the rate of growth did slow down from the 63% increase seen in the first quarter.As such, revenue in the six months ended 30 September was 56% higher than the year before at £217.26m (2010/11: £139.66m). Despite the slowdown, the 49% growth rate in the second quarter beat Singer Capital Markets' forecast of a 40% rise.However, the market will likely pick up on the measly 1% growth in UK sales in the second quarter, compared with a 15% increase in the first three months of the year.Nevertheless, international sales jumped by a whopping 150% in the first half, albeit with the second quarter growth rate tailing off slightly to 141%. International sales have now surpassed UK sales and account for 58% of total revenues. "I am pleased to report a strong first half performance. Our retail sales grew 60% over the comparable period, with our International business more than compensating for the economic challenges facing our UK customer base," said chief executive officer Nick Robertson.ASOS launched three more country-specific sites in the first half, in Australia, Italy and Spain, taking the total number of ASOS sites to seven."With costs and stock tightly managed and retail margin ahead of prior year, we are confident of achieving results in line with market expectations." The retail margin improved by 170 basis points over the six-month period.BC