[11] Kreer played 244 games in the DDR-Oberliga for the club, scoring 10 goals,[12] he holds the all-time record for the most Oberliga appearances in the history of 1.

[1] He debuted to the senior squad as the substitute for Matthias Liebers at 67 minutes of the match of the FDGB-Pokal 1978 2nd round against Motor Babelsberg under the trainer Heinz Joerk, on 14 October 1978.

FC Lok"[19] of three national players then; René Müller, Uwe Zötzsche and Ronald Kreer.

[22] Kreer, who kept fighting though with his nasal bone fractured from the early minutes of the match, jubilated and celebrated their victory running with the teammates under the flood of the over-fulfilled fans' roaring in Leipzig's Zentralstadion.

[29][30] He made his full international debut for East Germany on 22 September 1982 in a 2–2 draw against Bulgaria in Burgas.

[32] The second of the two goals was the decisive direct 25-metre shot for their sixth qualifying match of 1986 FIFA World Cup against France on 11 September 1985.

Legend Joël Bats was powerless, East Germany led 2–0 at 81 minutes of the match and won over the European champions.

[34] His last appearance is their last qualifying match of the 1990 FIFA World Cup against Austria in Wien Praterstadion on 15 November 1989, wearing the captain armband.

There was possibility left to qualify, the tables at that time: USSR 9:4 9:5, Turkey 12:8 7:7, East Germany 9:10 7:7, Austria 6:9 7:7, Iceland (8 matches completed) 6:11 6:10.

[35] On 9 November 1989 the Berlin Wall opened, the team hotel in Wien got surrounded by agencies like Reiner Calmund, hunting young talent at a low cost.

Kreer was sent-off at 75 minutes of the match for the attempted action after headbutt of Andreas Ogris, left the pitch and the team with 3–0 behind.