 <p>Yes, it does. The javadoc says:</p> <blockquote> <p>Closes this input stream and releases any system resources associated with the stream.</p> </blockquote> <p>And the wrapped stream is definitely such a system resource.</p> <p>Moreover, GZIPInputStream <em>is a</em> FilterInputStream, and the FilterInputStream javadoc says:</p> <blockquote> <p>Closes this input stream and releases any system resources associated with the stream. This method simply performs in.close().</p> </blockquote>