Extra gardaí were on duty last night in main centres all over the country as Halloween was celebrated with bonfires and fireworks.
A Garda spokesman said that superintendents in each area decided how many more personnel were needed, but extra gardaí were drafted in everywhere to keep an eye on events.
There were many calls to both gardaí and fire brigades about fireworks, bonfires and egg-throwing incidents.
A Dublin Fire Brigade spokesman said: "We've been hectic, really busy because of all the bonfires and fireworks."
In Cork city, a Garda spokeswoman said there were bonfires and fireworks but there was a lot of egg-throwing in the streets and that was causing problems.
Conditions were very foggy and motorists were warned by AA Roadwatch to slow down and be extra careful as children were out "trick or treating".
In Dublin, the first Halloween Festival in the docklands took place over the weekend as part of the Docklands Authority's plans to revitalise the area. Events included a North Wall Parade for children and, at George's Dock, there were seasonal market stalls laden with goods.
Street performers included eight-foot tall characters created by Wexford-based Buí Bolg theatre company. Crafts, ghost story-telling, angel card reading, and pumpkin-carving demonstrations also entertained the crowd.
In shopping centres all over the country, shows were put on for children who enjoyed face-painting and other activities.
In Shannon, anti-war activists used a Halloween theme in a protest at the airport. Two women wearing Iraqi mourning dress were described as "anti-war banshees".
Ms Zelda Jeffers and Ms Elaine O'Sullivan were arrested by gardaí. The women appeared at Ennis District Court after being detained within the security perimeter at the airport.