SÃO PAULO--Brazil's house prices declined for the second consecutive month in September amid slowing economic activity, high interest rates and elevated inflation. House prices fell 0.12% in September, according to the FipeZap index, which tracks housing prices in the country's 20 biggest cities. The index is produced by a think tank affiliated with the São Paulo State University. In August, house prices dropped 0.01%, the first nominal decline since the index started to be compiled in mid-2008. For the 12-month period ended in September, house prices picked up 2.63% House prices in the most desirable neighborhoods of Rio de Janeiro and São Paulo have doubled from 2008 to 2013, according to FipeZap. Real-estate prices in the country have lost traction as a sluggish economy as well as high inflation and interest rates hurt consumers' confidence. Brazil's economy is expected to decline around 2.80% this year, according to economists surveyed by the country's central bank. The benchmark Selic interest rate is currently at 14.25%. Write to Rogerio Jelmayer at rogerio.jelmayer@wsj.com This article originally appeared in Dow Jones Newswires