The national championship was divided into two half-year tournaments, the Torneo Apertura and the Torneo Clausura. Each was played on a home-and-away round-robin basis. The winners of each would play for the national title in a playoff. If the same club had won both tournaments, it would have won the national championship automatically.
Following-season Copa Libertadores berths went to the winner of each tournament, while the runners-up played for a Copa CONMEBOL spot. The bottom team on the aggregate table was relegated, while the eleventh place held a relegation/promotion playoff against the winner of the Segunda División (Second Division).
Updated to match(es) played on July 1998. Source: https://www.rsssf.org/tablesp/peru98.html Rules for classification: 1) points; 2) goal difference; 3) number of goals scored.
Updated to match(es) played on December 1998. Source: https://www.rsssf.org/tablesp/peru98.html Rules for classification: 1) points; 2) goal difference; 3) number of goals scored. (A) Advance to a further round; (O) Play-off winners Notes:
^Cienciano were docked 1 points for fielding 4 foreign players in Round 3.
Updated to match(es) played on December, 1999. Source: [citation needed] Rules for classification: 1) points; 2) goal difference; 3) number of goals scored. (O) Play-off winners Notes:
^Cienciano were docked 1 points for fielding 4 foreign players in Round 3.