Paul Kara had worn women's clothing - including leggings and blouses - to work at a council social services department for eight years, a London industrial tribunal was told.
But when he turned up twice wearing a skirt last April, managers at Hackney council in east London objected.
They told him he must wear men's clothing, and Mr Kara appealed to an industrial tribunal for a direction that this was sexual discrimination.
He argued that women in the office were allowed to wear traditional men's clothing, including suits, trousers, shirts and ties. His dress was equally appropriate, he maintained.
But the tribunal ruled that the council's action was not discriminatory.
After the decision , Mr Kara - pony-tailed but wearing trousers - told reporters: "I am saddened, but I hope it served to bring attention to the issue."
His wife, Helen, said: "It is unusual, but there have to be pioneers in every field. A hundred years ago it was very unusual for women to wear trousers."Reuse content