Oil and gas exports, which accounted for 93.5 percent of Algeria's total exports, declined 42.8 percent to $12.54 billion in the January-April period, according to customs figures issued late on Saturday.
The value of overall exports during the period dropped 41 percent year-on-year to $13.4 billion, the figures showed.
World oil prices have declined by more than half since last June as oil output has increased while growth in demand has slowed.