Awards for sex discrimination cases at employment tribunals have almost doubled in the last year to an average of £17,000.
The payouts were almost eight times higher than the average for other cases, according to the TUC.
Average settlements increased in most cases, including unfair dismissal and race discrimination.
Unfair dismissal cases brought by unions resulted in average payouts of almost £6,000 last year, with the highest award at £35,000. The ceiling for claims stands at £50,000.
Reducing the qualifying period for claims from two years to one is thought to have led to more cases being brought.
Compensation for race-related claims averaged £5,000. Unions are winning or settling more tribunal claims than ever before, with compensation totalling £14 million last year.
Around 95 per cent of cases taken up by a trade union were won at a tribunal or settled beforehand, the highest figure on record.
Where cases went all the way to a tribunal, 83 per cent were successful.
The number of cases taken to tribunals by unions increased 20 per cent to 6,478 last year.
TUC general secretary John Monks said: "Unions continue to win for their members and in many cases are winning more compensation than ever.
"Unions would prefer the number of tribunal claims to go down, not up, but the situation won't change until bad bosses start treating their staff fairly."
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