Mexico's gold exports were worth US$3.28bn in January-August, up from US$2.30bn in the same period last year.
Silver exports were flat at US$1.26bn, according to economy ministry data.
Gold exports were up from US$2.85bn in January-July, with silver up from US$1.05bn.
The 40% increase in gold exports comes despite lower production, with output falling 8.5% in January-July, compared to the same period of 2015, according to statistics agency Inegi.
August figures have not yet been released.
The higher exports in part reflect improved prices. Gold averaged about US$1,100/oz in January, jumping about US$100 the following month before reaching around US$1,340/oz in July and August.
By contrast, gold averaged around US$1,250/oz in January 2015, and traded in the US$1,100-1,200/oz range in March-August.
Miners may have taken advantage of the improved prices in July and August to export more gold.
Flat silver exports also reflect lower production offset by rising prices.
Output was down 4.4% in January-July, with prices increasing from about US$14/oz in January to US$19-20/oz in July and August. Silver traded in the US$15-17/oz range in January-August last year.
Mexico is the world's biggest silver producer and a top 10 miner of gold, copper, lead and zinc.