Four people were arrested in Dublin on Saturday night for "driving while intoxicated".
Gardai tested 300 people during MIT checkpoints across the capital for the May bank holiday weekend.
Two people were over the legal alcohol limit, while two others tested positive for cocaine.
Gardai have urged drivers to "stay safe on our roads this bank holiday weekend, reduce speed and never ever drink and drive".
New drink driving rules have left people confused about when it is safe to drive after enjoying a few pints the night before.
Drink driving limits in Ireland: How soon can you drive after pints, wine and shorts at Christmas
Drink drivers now face a three month driving ban if they get behind the wheel and are found to have a blood alcohol concentration between 50mg and 80mg.
This replaced previous legislation which had previously issued penalty points for some motorists.
Irish motorists have been warned against relying on off-the-shelf personal breathalysers.
The warning comes in light of increased early morning roadside checks by the gardai across the country.
Drinkaware has reported a sharp rise in queries from members of the public about driving the day after consuming alcohol.
We bring you more information with regards to drink driving limits in Ireland.
When is it safe to drive after a night of drinking?
Motorists warned against drink driving on St Patrick's weekend
Drivers have been advised that the time of their last drink at night will affect the amount of alcohol in their system in the next morning.
It takes an hour to process one standard drink and experts warn that there’s “no quick fix”.
One standard drink includes half a pint of beer, stout or lager, or a small glass of wine (100ml), or pub measure of spirits (35.5ml).
10 pints of lager/stout
If you have 10 pints of Guinness, Heineken, Carlsberg or some other lager or stout in and around 4.5%.
According to Drinkaware you can not get into the car for 20 hours after you finish your final drink.
So if you retreat to bed at midnight, you can not get back into a car until 8pm the following night.
1 bottle of wine
If you polish off one bottle of red or white wine you will have to stay off the road for eight hours after you finish.
10 vodka and cokes
If you are sticking to vodka and manage to down 10 altogether, that would mean no driving for 10 hours after your final drink.
12 pints and 6 vodkas with mixers
Going for a proper wild night, drink in the pub for the day and then go to a nightclub and switch to the vodka.
This one will have you feeling particularly bad the next day and that is reflected in how long you have to stay off the road.
You will have to avoid driving for 30 hours after your last drink, so basically just stay away from the car for the weekend.
How can I sober up quicker?
Gardai arrest motorcyclist after testing positive for cocaine and cannabis in Dublin
You can't.
Experts warn that there is nothing you can do to remove alcohol from your body any quicker apart from just waiting.
Common myths like drinking coffee or having a shower will sober you up are untrue.
Can I use a breathalyser to determine whether or not it’s safe to drive?
Drinkaware have warned against relying on off-the-shelf personal breathalysers saying they are not developed using the same standards as those used by the gardai.
Sheena Horgan, Drinkaware CEO, said: “The reality is that these off-the-shelf breathalysers are not developed using the same medical and safety technology standards as those used by officials like An Garda Síochána .
“This is a relatively new and unregulated space. Our advice echoes that of the Road Safety Authority , that we would have serious concerns about the validity of the results.
“While a personal breathalyser can be useful for information purposes, the results should not be taken as a clear indication that you are under the limit.
“There is still a potential chance that you will be over the limit if stopped at an official Gardai checkpoint.”
What is the drink driving law?
Gardai arrest lorry driver '12 times over alcohol limit' in Little Island, Cork
Ordinary fully licenced drivers detected by An Garda Siochana with a blood alcohol concentration (BAC) level of between 50mg and 80mg, will receive an automatic three month driving ban and a €200 fine.
The penalties for learner, novice and professional drivers remain the same at three months disqualification from driving and a fine of €200.
The law came into force on October 26 last year.
Ms Horgan added: “With almost 1,000 arrests for drink driving over the Christmas period, it’s clear that people are still taking the risk the following day.
“If you have even the slightest doubt that you are over the limit, there should be no justification for driving the morning after.
“Remember, the minimum penalty for drink driving is now a three month driving ban so the risk is simply not worth it. We all must play an active role in keeping our roads safe.”
