Cape Town - Scores of Nehawu members sang and danced outside Parliament's Plein Street entrance at lunchtime on Tuesday.
The protesters, including parliamentary staff, were demanding an investigation of "corruption, maladministration, and abuse of power by (parliamentary) management", the National Education, Health, and Allied Workers' Union said in a statement.
It claimed senior officials at Parliament had "colluded" against its members. The union wanted a meeting with National Assembly Speaker Baleka Mbete and National Council of Provinces chairwoman Thandi Modise.
"The complicity of... officials in flouting the labour laws and sabotaging the work of the Parliament is totally unacceptable," Nehawu said.
Parliamentary officials could not be immediately reached for comment.
Sapa