In 1903, Flatow assisted the founding of the Judische Turnerschaft, the historic and pioneering Jewish sports organization in Europe.

In 1933, Flatow was forced to "voluntarily" end his gymnastics club membership, as he was Jewish.

On 3 October 1942 Flatow was deported to Theresienstadt concentration camp in spite of appeals by the highly placed gymnastics official Christian Busch, where he died of starvation at the age of 73 before the end of the year.

[5] In 1997 Berlin honoured Alfred and Gustav Flatow by renaming the Reichssportfeldstraße (a lane) near the Olympic Stadium to Flatowallee (Flatow-avenue).

The Deutsche Post issued a set of four stamps to celebrate the 100th anniversary of the modern Olympic games.