Lojze Slak was born July 23, 1932 in the village of Jordankal, near Mirna Pec in the Dolenska region. He was one of 10 children, and because of his mother's ilness, had to spend much of his youth at his grandmother's house in Mali Kal. Little Lojzek moved to his grandmother's before he reached the age of one. As it turned out, the move would have a profound influence on his later years in life. Lojze spent much of his time with his uncle Ludvik who was a well known button box accordion player in the village. He played at many public festivals and celebrations and Lojze became infatuated with the instrument. Even before his first day at school, Lojze already knew how to play a dozen songs from memory. Uncle Ludvik taught him a lot, but he also encouraged him to learn to play the button accordion on his own.
At only fifteen years of age, Lojze began playing the button accordion as a solo performer at weddings. His performances impressed everyone and so he continued playing at weddings for the next ten years. It is difficult for him to recount all the weddings he performed at, but certainly there were more than a few hundred. Later in his life he confided that the weddings were likely the best musical schooling he could ever have had. At many of the weddings, he played alone, but occasionally he played with a group of musicians that became known as the Lojze Slak Trio.

The year of 1957 brought a significant change in his life and career. That year he had his first public appearance as an accordion soloist on a radio broadcast show called "Pokaži, kaj znaš!" (Show What You Know!). He not only impressed the professional musicians but also won the hearts of the general public. In 1959, he formed a quartet ensemble with his brothers, calling the group the Brothers Slak Ensemble. His brother Tone played the trumpet, Matija played the clarinet, Stane played the double bass and Lojze played the button accordion. They played together for three years, after which, brothers Matija and Tone had to serve in the army. That brought an end to the performances of the quartet. Lojze however would not give up and quickly found three new singers for his ensemble. He entered his ensemble in a competition for new music ensembles which was held at Gospodarsko Razstavišce in the capital city of Ljubljana. His song "Domaci Vasici" (To My Home Village) became an overnight best hit for Lojze Slak.
In the 1964 during a performance on Ljublana radio he encountered the singing group "Fantje s Praprotna". They hit it off, realizing that they had much in common and so agreed to do a few performances together. And that was the beginning of the rise of one of Slovenia's best known and most influencial musical ensembles.

After the breakup of the brother Slak ensemble, Lojze Slak moved to Ljubljana to look for work and earn a steady income. Among the jobs he held, he was a driver for the company "Petrol", he worked as a wall paper installer, and also worked for the furniture company "Hoja". He remained at the furniture company, and as a dedicated and loyal employee, worked his way up from a position of general laborer into sales, where he eventually retired.
In 1961, Lojze and his wife Ivanka gave birth to their first son Slavko. and sixteen years later to their second son Robert. In the seventies the Slak family moved from an apartment in Ljubljanskih Dravljah to a new house in Šentvid, near Ljubljana. In his heart, Lojze always yearned for his homeland in Dolenjska and so he built a cottage with a vineyard on hillside of Trška Gora. He has a special passion for his vineyard in Dolenjska, and every year he still produces a wine called Dolenjski Cvicek, for which he has already received numerous awards at the Novo Mesto Cvicek festival.