Throughout this period (up until 1991), the club was known as CLAS Casablanca which stands for Centrale Laitière Association Sportive and was incorporated into ONA, the largest holding in the country.

They finished 6th in the league standings in their maiden season and were invited to play at the 1989 Arab Club Champions Cup, going out at the preliminary round after finishing bottom of their group behind Étoile du Sahel and JS Kabylie, thereby missing the final tournament in Marrakech.

In 1988, the club finished last, losing to HUS Agadir (1-1 a.e.t, 2–4 on penalties) in the semi-finals and KAC Marrakech (1–3) in the third place playoff.

The team improved their performance in the following year (which was also the last edition), reaching the final before losing to FC Sochaux (0-0, 3–4 on penalties).

At domestic level, the club won their third Throne Cup title in 1992 at the expense of Raja CA in a rematch of the 1983 final.