In 1985, defender and occasional midfielder Bastiaan Poortenaar débuted in the first team of his youth club, SCHC (Bilthoven). In 1992, he made the move to HGC (Wassenaar), and three years later started playing for HC Klein Zwitserland (Den Haag). With HGC he placed 2nd in the Dutch domestic league (1992/93). In 1993, with HGC, he won the EuroHockey Cup Winner’s Cup, and was a runner-up in 1994. Between 1988 and 1995, Poortenaar collected 96 caps. As a defender, he scored two international goals, including a winning goal against West Germany in the 1989 Champions Trophy. With the Dutch team, Poortenaar placed second at the 1994 World Cup, the 1995 European Championships, and the 1989 Champions Trophy. At the 1992 Olympics, the Dutch team lost the match for bronze against Pakistan and ranked fourth.