Novel betaine salts of acetylsalicylic acid, namely 4-trimethylammoniobutanoate acetylsalicylic acid addition salt (gamma-butyrobetaine acetylsalicylate), L-carnitine acetylsalicylic acid addition salt and 3-(trimethylammonioamino)propanoate (meldonium) acetylsalicylic acid addition salt. Use of meldonium acetylsalicylate as antiplatelet agent for treating various pathologies induced by platelet aggregation, anti-inflammatory and antihyperlipidemic agent.