Modestas Pitrenas graduated from the Lithuanian Music and Theatre Academy twice: in 1997 he finished choral director studies, in 2003 – symphony and opera conducting. In 1990, Modestas Pitrenas founded chorus Psalmos and worked as its master until 2000. With this chorus conductor performed European music of various periods – from Renaissance to avant-garde. In 1995–1996 he attended the famous school of music and visual arts in Mozarteum, Salzburg (Universität Mozarteum Salzburg), where he received a bachelor diploma with commendation in chorus and opera conducting. Later he attended various seminars and mastership courses held by famous conductors, such as Esa-Pekka Salonen, Jorma Panula, Helmuth Rilling. Modestas Pitrenas won the First Prize, Gold Medal and Special Prize of Silesian Philharmonic Orchestra at the 7th Grzegorz Fitelberg International Competition for Conductors in Katowice, Poland (2003).

As a symphony conductor, Modestas Pitrenas prepared a fair amount of concerts with Lithuanian National, State, Lithuanian Music and Theatre Academy symphony orchestras, Lithuanian and Siauliai chamber orchestras, United Forces of Musicians from Klaipeda and Vilnius. For many years he had been working with North Rhine Westphalia Youth Symphony and Chamber orchestras. Modestas Pitrenas is also collaborating with famous soloists from Lithuania and abroad: violinists Tatyana Grindenko, Vilhelmas Cepinskis, Baiba Skride, violoncellist David Geringas, pianists Peter Donohoe, Petras Geniusas, singers Virgilijus Noreika, Liora Grodnikaite, and many others.

Conductor has recorded eight CDs with choral and orchestral music. Since 2000 Modestas Pitrenas conducts Bizet's Carmen and Weill's Three-Penny-Opera at the Klaipeda State Opera, as well as Strauss' Salome, Wagner's Die Walküre, Donizetti's L'Elisir d'amore, Portman's The Little Prince, and Theodorakis's ballet Zorba The Greek at the Lithuanian National Opera and Ballet Theatre. Since 2001 Pitrenas has worked as the Art director and Conductor of the Vilnius Balys Dvarionas Music School Student's Symphony Orchestra; since 2003 he has been teaching at the Lithuanian Academy of Music and Theatre, Conducting Department.

In 2006 Pitrenas has been appointed at the post of the Artistic Director and Chief Conductor of Kaunas City Symphony Orchestra. Currently he also works with the Lithuanian National Philharmonic and at the Lithuanian National Opera and Ballet Theatre.