Ventola signed for Inter Milan during the 1998–99 season, making 21 appearances in the league, and scoring 6 goals, playing alongside other notable forwards, such as Ronaldo, Roberto Baggio, Iván Zamorano, Andrea Pirlo, and Youri Djorkaeff, albeit mainly as a substitute. During the season, he showed real star potential for his young age, scoring 11 goals in all competitions, as well as a goal against eventual European Cup winners Manchester United in the quarter-finals of the 1998–99 UEFA Champions League. However, exactly a year later he was signed on a co-ownership deal with Bologna (after Christian Vieri's £32 million transfer to Inter Milan from Lazio) and later Atalanta during the next two seasons, in a swap deal with Corrado Colombo. During his loan period with Bologna, he made 14 appearances in Serie A, without scoring a goal, although he managed 4 goals in 7 appearances in the 1999–2000 Coppa Italia and the 1999–2000 UEFA Cup. With Atalanta, he had a more successful league season, scoring 10 goals in 28 Serie A appearances during the 2000–01 season.