Ants like your kitchen for the same reason you do -- because it contains food and water. When they come, they seldom come alone. They tend to march across counters and floors in long lines, and if they find a tasty bit of food, they may swarm all over it. Getting rid of ants, fortunately, is not too hard. Ant baits work very well. For people who want to avoid using pesticides, there are natural alternatives.
Clean the kitchen. Get rid of crumbs, sweep the floor, wipe up any water, and don't leave food out on the counter.
Find the place where the ants are entering the kitchen. If they are coming through a crack in the wall, seal it with caulk.
Set out ant baits near the ant trail close to where they are entering the kitchen. For best results, use several baits. Use commercial baits, or make homemade ones by combining a half teaspoon each of borax, honey, and sugar or sugar substitute, putting the mixture in jars, then leaving the jars open and on their sides near the ant trails, but out of reach of children and pets. You may notice an increase in the number of ants at first, but be patient and wait a few days. The ants take the bait with them back to their nest, potentially wiping out the entire colony.
Use non-toxic materials if you don't want to use poisons. Spray the ants with soapy water or vinegar. Instead of killing them, you can prevent them from getting too far into your kitchen by sprinkling cayenne, black pepper or cinnamon near their entry point. You can also place bay leaves there or draw a line with white chalk.