Around 200 local police officers protested outside Valencia's town hall to complain about a shortage of vehicles and equipment.
Also present at the demonstration were several 'go-go' dancers in underwear and union t-shirts, a move designed to highlight the city force's lack of new uniforms.
One brave officer turned up in bright blue long johns, Spain's El Mundo newspaper reported.
Police were using 30-year-old pistols, their bullet-proof vests were out-of-date and safety equipment for motorbike police was lacking, union officials told reporters.
The protest comes after an accident which saw four officers receive light injuries when the 17-year-old van they were travelling in allegedly suffered brake problems.
But Valencia's town hall has dismissed officers' claims, saying the driver of the van was at fault.
An official said the city's local police force had "everything it needs to carry out its duty," 20 minutos newspaper reported.